THE
A B C OF MINING
A Handbook for Prospectors

Treating fully of Exploratory and Preparatory Work of the Physical
Properties of Ores, Field Geology, the Occurrence and Associations
of Minerals, Methods of Chemical Analysis and Assay, Blow-pipe
Tests, Promising Indications, and Simple Methods of Working
Valuable Deposits, together with Chapters on Quartz
and Hydraulic Mining and especial Detailed
Information on Placer Mining, with
an Addenda on Camp Life
and Medical Hints.

BY

CHARLES A. BRAMBLE, D.L.S.,

Late of the Editorial Staff of "The Engineering and Mining Journal,"
and formerly a Crown Lands and Mineral Surveyor
for the Dominion of Canada.

ILLUSTRATED.

Chicago and New York:
RAND, McNALLY & COMPANY,
PUBLISHERS.

Copyright, 1898, by Rand, McNally & Co.

PREFACE.

Owing to recent rich discoveries in more than one mining field, hundreds of shrewd, intelligent men without experience in prospecting are turning their attention to that arduous pursuit—to such this book is offered as a safe guide.

A complex subject has been treated as simply as its nature permitted, and when a scientific term could not be avoided, the explanation in the glossary has been offered.

CHARLES A. BRAMBLE, D.L.S.

PREFACE TO SECOND EDITION.

A steady demand for this work has shown that it fills a want, and serves the purpose for which it was written. In issuing this second edition, a few compositors' errors that had crept in, owing to the author being in a very remote region while the book was going through the press, have been corrected, but no material changes in the text were found desirable.

CONTENTS.
THE A B C OF MINING.

A B C OF MINING.

CHAPTER I.
PROSPECTING.

Many men seem to think that should their destinies lead them into parts of the world where there is mineral wealth they will have little chance of discovering the deposits without the technical education of a mining engineer. This is wrong. The fact is that the sphere of the prospector does not cover that of the engineer. The work of the one ends where that of the other begins, and many of the most successful discoverers of metallic wealth have been entirely ignorant of the methods by which a great mine should be opened, developed, and worked.

A few simple tools and a not very deep knowledge of assaying, with an observant eye and a brain quick to deduce inferences from what that eye has seen, are the most valuable assets of a prospector. In time he will gain experience, and experience will teach him much that he could not learn in any college nor from any book. Each mining district differs from every other, and it has been found that certain rules which hold good in one region, and guide the seeker after wealth to the hidden treasure that has been stored up for eons of time, do not apply in another region.

To show what may be done with imperfect, improvised apparatus, an Australian assayer, who has since become famous, started up country in his youth with the following meager outfit: A cheap pair of scales, a piece of cheese cloth, a tin ring 1½ inches by ½ inch, a small brass door-knob, some powdered borax, some carbonate of soda and argol, a few pounds of lead lining taken from a tea chest, an empty jam pot, a short steel drill, a red flower pot. With this modest collection of implements he made forty assays of gold ores that turned out to be correct when repeated in a laboratory.

About the best advice that can be given to a man who has determined to go to some out of the way region where there is a possibility of his discovering minerals is to recommend him to visit the nearest museum and gain an acquaintance with the common rocks. Should he be unable to do this he had better provide himself with small, inexpensive specimens from the shop of some dealer. It is almost impossible to teach a beginner to distinguish the various rocks by any amount of printed instruction; the only way to learn to recognize them is to handle them and note carefully their color, weight, and the minerals that go to make them up. The explorer should be able to recognize at a glance, or at any rate after a very short inspection, the sedimentary rocks, such as sandstone and limestone; the metamorphic rocks, that is, rocks that have been altered by the agency of great subterranean heat in ages long past, and which were probably stratified rocks at one period, such as granite and gneiss, and the truly igneous rocks—trap, diabase, diorite, etc. He must know also that mysterious rock which the western miner calls porphyry, and to which is ascribed most wonderful virtues in the way of ore attraction; while dolerite and dolomite must be to him familiar terms and substances. This sounds easy enough but the student will find that a good deal of hard work is necessary before he can readily recognize each of these rocks.

It is even more necessary that he should learn the metals thoroughly. Each one differs from all the rest in some particular. Often this difference will be an obscure one, but to the careful investigator the recognition of the substance will be in the end certain. They may differ in weight, in color, in hardness, in a dozen different ways, so that to the man who has made a study of this subject a determination is always possible.

On account of the wonderful discoveries in the Canadian Northwest and in Alaska, the eyes of thousands are turned towards those fields. Wonderfully rich placer ground has already been found and there can be no reason to doubt that very much larger areas remain unproved. Where this gold comes from is an open question; geologists, mineralogists and chemists, not to mention mining engineers and practical prospectors, have disputed over the source of the gold already found, but it must be confessed that there are almost as many theories as there are disputants. Could it be known with certainty how and under what conditions the gold got where it is found, the problem of seeking for it might be made easier. Unfortunately this is not the case, and all prospecting for the home of the precious metal is more or less a groping in the dark. We do know that the heaviest particles of gold do not travel far from where they were first deposited, because gold is so enormously heavy—its specific gravity being about nineteen times that of water—it seeks the bottom of the stream and stays there. It is not an invariable rule that the gold increases in coarseness as the stream is ascended, but it is a very general one. On some rivers rich and poor stretches of gold-bearing gravel succeed one another as the explorer makes his way up or down stream. This is difficult to account for, but in many cases is believed to be caused by the modern river robbing the bed of some one or more ancient water-courses whose beds crossed the valley of the present stream. This may or may not be the case. We only know that the miners who found coarse gold on the lower regions of such rivers as the Frazer were miserably disappointed when they reached stretches near the source and found nothing but flour gold. This same feature has been noticed in some of the Alaskan rivers. It is quite within the bounds of probability that no very rich quartz veins exist in Alaska. It does not follow from the richness of the placers that the gold is derived from very rich quartz lodes, because this amount of gold may really represent the product of a vast amount of rock that has been ground to powder and washed away in the course of ages. The gold would not travel far, and the deposits being unearthed to-day have been accumulating in these northern streams since the world was young; water-courses are nature's ground sluices.

It is possible that one stream has cut through the drainage of another. Sometimes this has impoverished the first and enriched the second, while in other cases the reverse has obtained. Upheavals have formed faults[1] and fractured the strata, and the gold may have been deposited by solution in these fractures. Often the soil will have been washed away from near the top of the mountain, so that layers of stratified rock are seen to be duplicated on each side while they are covered at the summit. The prospector keeps his eye open as he goes along and notes carefully the character of the fragments of rock he finds in the streams. Quartz, diorite, diabase, and porphyry pebbles are grounds for expecting a profitable result, but of course there is no certainty of such a happy issue. As soon as the district begins to be fairly well known certain discoveries are made that invariably render prospecting easier. Local peculiarities are noted; certain characters are found to be common to the ore-bearing bodies or deposits; the lines of deposits become known, and a good deal of light is then shed upon a very difficult problem. As a rule, when the fragments of quartz, pyrite, chalcopyrite, or galena are rough, they have not traveled far, and the lode from which they have been derived should be close at hand. Water and attrition soon round these minerals on their sharp edges, and thus show that they have come from some little distance.

In some countries, especially where vegetation is scanty, the outcrop of a body of mineral may be traced by a difference in the vegetation. In South Africa a chain of pools usually follows the course of a line fault, which in its turn marks where an intrusive lode carrying mineral separates two different formations. As a rule, any heavy mineral is worth investigating. Even in remote regions silver, mercury, tin, nickel, platinum, copper, and several other metals are worth paying attention to. If they are too far away from the railroad or the steamboat to-day they may not be so next year, for civilization advances with giant stride in these days and never faster than when transportation companies are reaching forth to some newly discovered mineral field.

One of the greatest drawbacks to prospecting in the North is the dense growths of moss and forest that cover the ground. In most of the Western states, in South Africa, and in Australia this drawback does not exist and prospecting was by that much the easier. However, as a compensation, there is abundant water in Alaska and the Northwest, while it was and is almost entirely absent in several other regions that possess immense bodies of ore which are not available for this very reason.

Quartz has been called the mother of gold, and certainly quartz and gold are inseparably connected to-day. As to where gold may be found the best reply that can be given is in the words of the old miner, who, when asked that question, said: "Where it be's; there it be's," and then added, "and there ben't I."

Although most prospectors travel alone from sheer necessity, there can be no doubt that three or four men forming a party and working together have the advantage. They can do their work cheaper, more thoroughly, and more surely. By co-operating they may carry a more complete outfit. Should any accident happen help is at hand, whereas the solitary wanderer often dies as the result of some accident that would have been trivial had he had a companion. Three or four claims may be worked in conjunction with one another at far less proportionate expense than a single one could.

Nature's preparation for the reception of great ore deposits is somewhat as follows: The crust of the earth is prepared for the reception of the metals by great outbursts of igneous or melted rocks; the metals themselves being carried in suspension in the heated water that everywhere traverses the strata. These metals are deposited in the veins as soon as the waters begin to cool, and the pressure to which they were subjected from deep down in the earth's crust is removed. A great mineral country is usually marked by the outcrops of the veins being persistent in their courses and traceable for many miles, though very probably many breaks may occur in these outcrops. The rocks associated with great ore bodies are lime, porphyry, granite, shales, slates, quartzites, and diabase. Fragments of mineral and gangue, known to the miners as float, may be littered over the hills and encumber the courses of the stream. A central line of eruption may often be traced by masses of altered rock, and beds of lava or other volcanic products. We find the granite has been melted and the limestone has acquired magnesia, and thus become dolomatized.

Whenever a heavy deposit of pyrites, or mundic, is found mineral probably exists below. The cubes of pyrite are not always valueless, they may contain gold in addition to the iron and sulphur. When the pyrites decay under the influence of the weather, and leave the quartz honeycombed, these cavities often contain concentrated gold; for which reason you often get a higher assay from the surface than from any point lower down in the vein. In sinking the shaft soon gets below this altered quartz and the ores are then combined with sulphur. They have become sulphides, and are harder to treat. The prospector should therefore act very cautiously when trying to develop a mine with a small capital behind him; because, although the first ore may be adapted for stamping, he may find, before he has gone down fifty feet, that it can only be treated in a smelter, and that all the money he has put into crushing apparatus is wasted.

Without the prospector there would be no mining and the world would yet be in the stone age. He is not appreciated at anything like his real worth. He requires ability and experience, push and perseverance. Prospecting is a search for valuable minerals. He may not be very deeply learned in either geology or mineralogy, but he must have a keen eye and good natural powers of observation.

There are some sixty or seventy elements in the world, and the most common is oxygen. Nearly all the coloring matter of rocks comes from iron. Wind, frost, rain, snow, and heat, cause a crumbling of the different rocks, and running water wears them away, and carries off and distributes the particles. By this agency, and by floating ice, they are often removed to long distances. The action of internal heat renews the deposits of mineral by eruption, or by hot springs, but this means of renewal was much more powerful in the past than it is now.

Organic matter found in the crust of the earth was derived from animals or vegetables. Coal is a legacy from forests that flourished ages ago, while petroleum is all that remains of vast schools of fishes that swarmed in Devonian seas.

Stratified rocks are either sand, clay, or calcareous, which means lime-bearing. In their natural position they were horizontal, but owing to subsequent volcanic action they are, in some localities, tilted at all conceivable angles. The eruptive rocks have burst through them in places, changed their character, divided them by intrusive masses, and generally enriched them with mineral deposits.

Everything now known points to the theory that the contents of veins were deposited in the lodes by infiltration. In a few instances famous mines have no veins, but are literally hills of mineral; they are then of low grade, but much more remunerative than average high grade mines, owing the vast quantity of ore, and the ease with which it can be mined. The famous Treadwell mine, on Douglas Island, Alaska, has ore that is worth less than four dollars a ton, but it is quarried, and 640 stamps work day and night. There is about a dollar a ton profit, and hundreds of thousands of tons are treated annually. The tin mine known as Mount Bischoff, in Tasmania, and the Burra copper mine in Australia are other instances. Each of these deposits was found as an outcropping on the bare top of a low hill, and none of them has walls.

A fault may throw the vein up or down, and a good deal of exploration may have to be done before it is recovered.

A lenticular vein consists of a series of double pointed ore bodies like lenses which may be strung out, overlapping, or not.

The outcrop of a vein is never the same as its strike, except on a level surface.

A stringer of ore branching off from the main vein is known as a chute, shoot, or chimney.

In developing a ledge or lode, first find out what the ore is. Gold is shown in the mortar, especially after roasting. Silver may be recognized at sight, or by assay tests, or blow pipe; copper, by its vivid colors,—green or blue for carbonate and red for oxide or metallic copper. The ore often differs in various parts of the vein. Explore your lode along the surface, across, and down its dip. When you find it continuous it will be time enough to think of a vertical shaft. The top of a shaft must be timbered with logs, so as to give sufficient fall to get rid of the mineral when it is hoisted.

The first thing the prospector has to consider is his outfit. The more complete this is the better, but ninety-nine times out of a hundred the difficulties of transportation in a wild region are so enormous that he will have to do without a great many things that he would like to have. He must endeavor to make up for the lack of tools by ingenuity; then he may get along fairly well. A pan, he must have. In this he will wash carefully all his samples. Then, a flask of quicksilver is more precious to him even than gold; for, having it, he can resort to pan-amalgamation, which will save the precious metal even when it is in minute particles.

This process may be described as follows: A pound or two of the ore in powder is placed in the pan and water is added until the mass becomes a thin pulp. One ounce of quicksilver and a small piece of that deadly poison, known to the chemist as cyanide of potash, and as prussic acid to the ordinary man, should be added, and the mass should be stirred thoroughly, for two hours if you can stand it. Then turn in water and wash off the dirt and the amalgam will be found in the bottom of the pan. This you must collect very carefully. You should have a square piece of chamois skin or a piece of strong white cotton cloth. In either case the amalgam is put in the center of this square and the cloth twisted until all the superfluous quicksilver is pressed out and your amalgam remains nearly free from mercury. This amalgam placed on a shovel and held over a brisk fire will soon show the yellow color of gold. If you have no mould you may make one of clay, put your gold therein with a little borax, and very soon, the fire being hot enough, you will have a tiny ingot of the precious metal. But most prospectors are satisfied when they have obtained their sponge gold, and do not carry their operations further in these rough and ready tests.

The prospector of to-day is often a very different man from his predecessor of a generation ago. The old gold hunter used to sally forth armed with a pick, shovel and pan, and usually a very little grub. In his stead men are now taking the field who have had the benefits of a thorough education, both practical and theoretical, and provided with all the equipment necessary for their work. Some of these men carry an outfit somewhat as follows: An iron mortar holding half a gallon, together with a pestle a rough scale for pulp, a more delicate one showing troy grains and pennyweights, a 40-mesh sieve, a burro furnace and muffle, one cupel mould, a couple of dozen scorifiers, tongs to handle the cupel and scorifiers, two annealing cups, a spirit lamp, a dozen test tubes, a pouring mould, five or six pounds of borax and about as much carbonate of soda, five pounds of bone ash, ditto of granulated lead, a pint of nitric acid, ditto of hydrochloric acid, ditto sulphuric acid, ditto of ammonia, twice as much alcohol and two pounds or so of granulated zinc.

As a blow pipe outfit he will take a blow pipe, spirit lamp, nitrate of cobalt in solution, cyanide of potash, yellow prussiate of potash, red prussiate of potash, a sheet or two of filtering paper and a couple of three-inch glass filters. With this outfit he can determine any mineral he may come across.

By patience and observation the man who starts out to take up prospecting as a road to fortune may easily master the rudiments of his business. It will not take him long to become familiar with the commoner rocks, and the more valuable ores. His own rough tests in the field must be confirmed by competent assayers upon his return to civilization, and in this matter he should be very guarded. The most reliable assays are made either at the different government assay offices or by some of the large metallurgical works whose reputation is world wide. Prospecting is hard work, but the life is healthy and full of excitement, only the explorer should have courage, hope, and good temper, for each and every one will be as necessary in his chosen vocation as his pan and pick.

When alluvial or placer gold has been found it is reasonable to suppose that the vein from which it was derived may also reward diligent search, for it is undoubtedly true that most placer gold has come from quartz veins. This, however, is believed not to be invariably the case, a recent school of mineralogists contending that pure masses of alluvial gold have been formed from the accretion or growth of the gold deposited from certain gold salts. This is in any case probably exceptional, and the prospector who finds gold in gravel should seek in the adjacent country for the quartz lodes from which it came.

Important deposits may be expected at or about the line of unconformability where slates, shales, quartzites, sandstones, limestones, schists and other sedimentary deposits are pierced by intrusive masses of igneous rocks.

Veins filling the cracks that once existed between two differing rocks are known as contact veins. Such veins are often very rich. Curiously enough large masses of true igneous rock rarely contain valuable deposits of mineral, but where such intrusive masses cut dikes or walls of porphyry, or diorite, the region is worthy of careful investigation.

POCKET LENS.

In an open country the prospector should keep to the hill tops if on the lookout for veins, as the outcrops show more distinctly on the bare ridges, but alluvial deposits are only found in valleys and along the borders of streams. In any case, much of the northern part of this continent can only be prospected by following the streams, on account of the dense growth of forest with which the soil is covered. The true line of strike of a vein can be determined only on a level stretch. The line of strike and the line of dip are always at right angles to one another; the outcrop may follow the strike or it may not.

A pick, shovel, and pan, are absolutely necessary to a prospector's proper equipment. A good pocket lens, cheesecloth screen, and small iron pestle and mortar are often useful. The pan is the most essential part of the outfit, and is always bright from use.

The regular gold miner's pan is 13¾ inches in diameter across the top, 10 inches across the bottom and 1/8 inches deep. The best are made of sheet iron and have a joint around the bottom rim which is of some assistance in retaining the spangles of gold.

A more primitive instrument than the pan is the batea. This requires more skill than the pan, and is much in favor with South American miners. It is made of hard wood, 20 inches in diameter, 2½ inches deep in the center, inside measurement, and sloping gradually to nothing at the sides.

The horn spoon has been handed on from antiquity. It is made from a black ox horn, at least a black one is the best as it shows the gold better; it is eight to ten inches long by three inches wide, cut off obliquely.

When gold is suspected in quartz, but there is visible to the naked eye more or less iron, copper, and other base metals, it is well to crush the quartz into coarse fragments. Roast on a shovel or other convenient tool over a hot fire, and finally pulverize in the mortar. If panned it will now reveal much of its gold, while, had these measures not been taken, the sample might have given negative results and been declared valueless.

After pulverizing, the ore should be passed through the cheese cloth screen before panning. If the approximate value of the ore is sought, the sample must be dried and weighed before crushing; and the resulting gold weighed. Thus:

Sample is to 2,000 lbs. as gold found is to Ans.

About 13 cubic feet of quartz weigh a ton before being disturbed; when broken to medium sized lumps 20 cubic feet may be taken as representing a ton. Although experience teaches the miner to estimate very closely the value of his sample, it is better for the tyro to have a small pair of scales with grain weights. A grain of gold, if tolerably pure, is equal to four cents. Above all things avoid the too common error of panning the pick of the rock, as a false estimate is bound to follow and only too probably eventual loss.

A yard of gravel before being dug makes one and a half yards afterwards. A pan of dirt is usually about 20 pounds, although it is not well to fill quite full in actual work.

Many a valuable mine has been found by following up "float" ore. Float is detached fragments of the vein or gangue, and it becomes more and more abundant as the lode is approached until it finally ceases abruptly. This indicates that the vein has been reached or passed, and a trench dug throughout the alluvial soil at right angles to the assumed line of the vein will probably reveal it. The float and mineral of course drift down hill; if the side of the mountain be saddle-shaped the float will spread out like a fan as it washes down, but if concave the force of gravity will concentrate it within a narrow space in the ravine. Float found at the foot of a hill has come, as a rule, from that hill. The nearer the vein the less worn will be the edges of the float and mineral. The gangue or vein-rock in which the metal is found may be calcite or calc spar, fluor spar, heavy spar or baryta, or quartz. Gold is almost always found in this last matrix. The upper parts of most quartz lodes are usually oxidized, that is to say, the atmosphere has acted upon the iron pyrites, freeing the sulphur and staining the quartz yellow, red, or brown, by oxide of iron. This is known as "gossan" or the "iron hat." Such quartz is frequently honeycombed and rotten. Below the water level these veins run to sulphides in which decomposition has not set in, and the gold contained in the quartz is no longer "free milling," i.e. will not give up its gold to mercury without a preliminary treatment.

Whenever the explorer comes across a mass of gossan he should sink a trial shaft to the vein, as it is almost certain that below the oxidized sulphides a body of mineral exists likely to encourage mining operations.

Native gold is malleable, will flatten out under the hammer, and a steel knife will cut it with ease. It almost invariably contains silver, sometimes to the extent of one-fifth. A little practice will enable the prospector to recognize it, for there is but one king metal. Much gold is derived from copper and iron pyrites, and silver and lead ores are a very large source of supply.

Gold is found in gravel of every variety, from finest pipe-clay to boulders weighing tons. Sometimes volcanic eruptions have covered these deposits since the ancient rivers laid them down, and in many cases their courses do not in the least agree with the valleys of the shrunken streams that have replaced them.

Gold may be distributed through the whole thickness of a bed, but ninety-nine times out of a hundred the richest layer of gravel is just above the bed rock upon which all the gravel rests. Gold may even be found among the grass roots, especially in dry localities where there has been little water to carry it downward. When the bed rock consists of upturned slates the gold frequently penetrates it for some little distance.

Sand is nearly always poorer than gravel.

The experience of miners in the Victoria gold fields is that gold is always found on the bars or points, and not in the deep pools and bends.

The great difficulty with which any but the very finest particles of gold can be moved by water accounts for the value of the deposits depending largely upon the local rocks. It is very fortunate that gold's specific gravity is so great, for were it less its recovery would be much more difficult. The sluices and other apparatus of the miner are really nothing but the operations of nature imitated on a much smaller scale. There is one thing, however, time, that nature can afford to expend in prodigious periods, while man must not waste a single minute.

It not being possible to point out where the ancient river beds lie, smothered as they are by hundreds of feet of overlying drift, lava, and other later deposits, the only feasible plan is a series of boring with the diamond drill.

When gold has been discovered the finder must act with the greatest prudence, for even gold may be bought too dear. The surest test is a mill run, that is passing 10 to 50 tons through all the operations of crushing, milling, roasting, amalgamating, etc., and so ascertaining what returns are likely to be obtainable when the deposit is worked on a commercial scale. True sampling is necessary. All parts of the vein should be included, and the lode cross-cut by galleries in more than one spot. It is the very great necessity of these expensive preparatory explorations that has given rise to the saying, "Quartz mining is for rich men."

Many gold mines have been abandoned as unprofitable that could have been mined at a profit had their owners been wealthy and enterprising enough to do a great deal of expensive prospecting by diamond drill, cross cuts, drifts and rises. In one instance that came to the writer's knowledge a clever mining engineer cleared nearly $200,000 profit by leasing for a term of years a gold mine that was supposed to be exhausted. A drill hole sunk less than 50 feet below the old workings revealed a pocket of ore in the vein, and paying quartz was found for many hundred feet below.

With the improvements in electricity made recently a cheap power has been provided that will permit many mines to be reopened. The saving in working expenses effected by introducing electricity is often very large; after the plant is once installed the cost is almost nil where turbines can be employed to furnish the power to the generators. Machinery capable of delivering power at a distance of several miles from the plant, may be operated at very reasonable cost as compared to that of other prime movers.

Discoveries of many deposits that have in time been successfully mined were the result of chance. No skill guided the finder; he merely stumbled upon his luck just as the wayfarer once in a while hits his toe against a well-filled pocketbook. For instance, a South Australian squatter picked up a piece of copper ore that a wombat had thrown out of his burrow, and the result was the discovery of the great Wallaroo lode. The first diamond from South Africa was picked up by an ignorant bush boy and kept with a lot of worthless pebbles in the private collection of the boy's master; no suspicion existed of its value until a passing trader had carried it away and obtained $2,500 for it in Capetown. Gold was first discovered in California in 1848 by the superintendent of a sawmill who saw it glistening in the flume. Similarly gold was discovered in both Australia and Brazil by the purest chance. Had not a tree been uprooted by the wind the vast deposits of soft hematite iron ore in the Biwabic iron mines of the Mesabi range, Minnesota, might have remained unknown for many a long year to come. In the desolate region to the northward of Lake Huron great stores of nickel ore exist. These mines, which may some day regulate the price of the metal all the world over, were exposed in a railway cutting; no one dreamed of their existence. The Redington quicksilver mine in California was discovered by some roadmakers. Tradition relates that the enormously rich silver mines of Potosi, in Bolivia, were discovered by the accidental uprooting of a bush having spangles of silver ore attached to its roots. This was in 1538, and two hundred years later a similar streak of luck revealed the wealth of the Catorce district of Mexico, from which in thirty years, ore to the value of $35,000,000 was taken.

Moreover, the search for one mineral often leads to the discovery of another. The Comstock lode was first worked for gold, and the miners threw away the black sulphide of silver worth $3,000 to the ton. The Broken Hill mine in Australia was claimed as a tin deposit by its finder; it is now the greatest silver producer in Australasia. Such instances could be multiplied almost indefinitely, chance entering into a majority of mineral discoveries. On the other hand, it has happened, not infrequently, that purely scientific deductions and calculations have brought to light stores of mineral wealth.

Certain minerals are likely to be found associated. Cassiterite goes with boron and tourmaline, topaz, fluor spar and lithia-mica; all containing fluorine. It is also found with wolfram, chlorite and arsenical pyrites. Magnetite is often accompanied by rocks containing garnet, epidote and hornblende. Zinc blend and galena may occupy the same vein, which is likely to be of baryta or heavy spar. Much galena carries silver. Gold is associated with many metallic sulphides such as iron, magnetic, and copper pyrites, mispickel, galena, blend, stibnite and tetrahedrite. Gypsum accompanies salt.

Surface indications may be described as: Form of ground, color, outcrop, decomposed and detached mineral, mineral deposits from springs, altered or peculiar vegetation and other similar guides. A hard quartz outcrop often stands up like a wall and is traceable for miles. The Rainbow silver bearing lode of Butte, Montana, stood 20 feet above the surface. Soft minerals, such as clay, are cut into and sunk below the surrounding level. Deposits of Kaolin or China clay are usually so found.

Any special bright coloration of the rocks of a district merits investigation. Copper gives green, blue, and red stains; iron, red or brown; manganese, black; lead, green, yellow or white; cobalt, pink; cinnabar or quicksilver, vermilion. The nickel deposits of New Caledonia were made known to the world by the explorer Garnier in 1863, his curiosity having been aroused by the delicate green coating given the rocks by an ore containing water, quartz, nickel and magnesium.

Hard beds of shale decompose on the surface into soft clay, and a still more noticeable change is the conversion of ores containing sulphur into oxides. This chemical change causes the gossan or "iron hat," for which token of underlying wealth the prospector should be eternally watchful. This alteration may extend downward four or five hundred feet from the surface, but in such cases the true weathering has ceased long before the limit of discoloration is reached, and the change of substance is due to the filtering of surface waters through the vein.

Gossan varies greatly in its nature. Galena becomes anglesite, cerussite, pyromorphite and mimetite. Copper pyrite changes into native copper, melaconite, cuprite, malachite, chessylite, or perhaps into a phosphate, arsenate, or silicate of the metal. Carbonate of manganese gives the black oxides and silver sulphide ores are, after weathering, known as native silver, kerargyrite and embolite.

The ore in the gossan is very generally more valuable than it will be below, and this is especially true of gold and silver ores. The gold having been set free from the close embrace in which the iron pyrite held it previous to the latter's oxidation, it is now readily caught by quicksilver. Silver under similar conditions becomes chloride, and likewise amalgamates without difficulty.

Seams containing native sulphur often show no trace of that element on the surface, having weathered into a soft, white, gray or yellowish-white granular, or pulverulent, variety of gypsum.

Veins of asbestos often decompose into a white powder found in the crevices of the rocks; fibrous asbestos existing in the interior.

Petroleum shows in an iridescent film upon still pools, and the odor is a sure guide to its nature.

A "dipping-needle" is valuable to the prospector on the lookout for iron ore; by its use he may discover masses of magnetic ore and trace their extent. As he carries the compass over the ground the needle dips toward any iron mass he approaches; directly over the ore it becomes vertical.

MINER'S DIPPING NEEDLE.

In a wilderness country strength of body and endurance are important qualifications. The prospector must, moreover, have such general knowledge of geology and mineralogy as to be able to recognize all valuable minerals and confirm his conjecture by simple tests. Pick, shovel and pan must be handled skillfully, while the rifle, shotgun and paddle must also be understood. For in the unsettled parts of the country the traveler must even yet rely to some extent upon the fish and game he may be able to secure, and every old prospector becomes a trained hunter and camper. Knowing how to bake bread is sometimes more valuable than much mathematics; ability to build a rough boat is often the one hope of salvation.

In sinking a short shaft in a sunny country a large mirror, inclined at a suitable angle over the shaft, will give sufficient light.

Lodes or veins following the general trend of the auriferous quartz are much more likely to be rich than are those that cross it. Gold is never distributed evenly in veins, though it may be in great beds of low grade material; but more often rich areas alternate with barren portions.

Where quartz veins are small and the rich pockets separated by wide intervals of poor gangue the gravel of the district will usually be similar in character. As this condition obtains in the upper Yukon district as far as the gravels are concerned, it will probably be found to hold good for the quartz leads, when they shall have been discovered.

The more nearly the gold formation approaches to the crystalline schists, the poorer will the quality of the gold be through the larger percentage of silver found in it. In slates the proportion may be 22 gold to 1 silver; in schists it has been known to be a ratio of 1 to 1.

With the discovery of valuable gold-bearing gravel on the bare hillsides of the Northwest, a vast region has been added to the area the prospector may explore to advantage. No experience acquired in ordinary American placer grounds is likely to be of much use in detecting these higher gold-bearing gravels of the Yukon, but they appear to be somewhat similar in character to the New Zealand terraces. Terrace-prospecting requires perseverance and the use of some brains, as it is infinitely harder than creek-prospecting. These terraces or benches are the remains of old river beds. The whole bench must be carefully scanned over because the gold is quite as likely to be in one part as in the other. Sometimes it is in half a dozen different layers one above the other. Sometimes the old river terraces are entirely covered by landslides, and the majority of such deposits are not likely ever to be found, as it is almost impossible to guess at locations.

In New Zealand gold has been found on table-lands nearly 6,000 feet above sea level, and according to recent information valuable claims have been discovered in Alaska on the very summits of the rounded hills on each side of El Dorado creek.

To understand how such deposits as those of the Northwest may have been made, suppose that such a vein as that of the Idaho, which has been worked for a depth 1,700 feet by a width of 1,000 feet, and from which $17,000,000 have been taken, to have been worn down by glacial or other forces. Is it not conceivable that the gold would gradually have accumulated in the nearest canyon?

DOLLY.

To obtain suitable samples of the vein a dolly is an efficient apparatus.

This is practically a very simple, crude, stamp mill. On the end of a solid log, firmly fixed in the ground and standing four feet or so above the surface, a square 6-inch hole is cut in which are fitted wrought iron bars 3 inches deep by ½ inch wide, and separated by equal intervals. These bars taper below so as to permit free passage of the pounded mineral. A wooden box surrounding the grating keeps the ore in place. A block of wood, shod with iron, forms the stamper. The miner hauls on the handles at every blow. The gold is saved on the lower table.

No one of experience in mining would look for brown hematite in a granite range, nor for black band, though such might be a likely region for red hematite or magnatite.

The explorer should be familiar in theory at least with the locality where he may expect to find valuable minerals. For instance, should he be searching for some heavy, detached substance that is usually found in placer deposits he will keep to the low ground and examine carefully the beds of the streams. On the other hand, should his quest be for some ore that is more properly a component of a lode or vein he will examine the side hills and summits where denudation will certainly have exposed such deposits. Then he must know the appearance of each ore, and with the methods of making rough and ready tests he must be perfectly familiar.

Gold is always more or less intimately associated with quartz. Oxide of tin is said never to have been found more than two miles from some granite rock, one of the components of which was muscovite or white mica. The junction of slates and schists with igneous or metamorphic rocks often proves a valuable find of mineral.

Rocks for the purposes of the explorer may be grouped under three heads: Igneous; metamorphic; stratified. The first includes lavas; trachytes, grayish with rough fracture and mainly glassy; dark basalts: and traps, such as greenstone. Obsidian is a volcanic glass. Metamorphic rocks are thought to have once been stratified, but to have been altered by heat. They comprise granite, of quartz feldspar and mica; syenite, containing hornblende instead of mica; gneiss, like granite, but showing lines of stratification; mica schist, made up of mica and quartz and separating easily into layers; slates.

Stratified rocks are those deposits from water, such as sandstone, limestone, clay, etc.

A prospecting shaft need not be of large dimensions. One 4 feet square is amply large for any depth down to 30 feet, but it must be kept plumb.

Sometimes shafts are sunk through the pay streak in alluvial gravel, without it being detected. Frequent panning will guard against this mistake.

In the Klondike region it is said early prospectors missed very rich deposits, that have since been discovered, by stopping short of true bed rock, being misled by a bed of harder gravel that they thought was bottom.

Silver almost invariably carries some gold. The dark ironstone hat already referred to is a good indication of silver ore beneath; it is generally composed of conglomerates cemented by oxides of iron and manganese.

Galena, which is sometimes so rich in silver as to be worth working for that metal, may often be followed by surface indications; namely, a white limy track with detached fragments of float ore in the surface soil. The blowpipe or fire assay quickly determines silver ore.

Tin in lode, stream, or alluvial deposits occurs only as an oxide, but its appearance is varied. It may be almost any color and shape. It is always near granite, containing white mica known as muscovite.

The minerals for which it is most easily mistaken are:

The magnetic or dipping needle is used in New Jersey, as follows, according to the State Geologist, W. H. Scranton, M.E.: "An attraction which is confined to a very small spot and is lost in passing a few feet from it, is most likely to be caused by a boulder of ore or particles of magnetite with rock. An attraction which continues on steadily in the direction of the strike of the rock for a distance of many feet or rods, indicates a vein of ore; and if it is positive and strongest towards the southwest, it is reasonable to conclude that the vein begins with the attraction there. If the attraction diminishes in going northwest, and finally dies out without becoming negative, it indicates that the vein has continued on without break or ending until too far off to move the compass needle. If, in passing towards the northwest, along the line of attraction, the south pole is drawn down, it indicates the end of the vein or an offset. If, on continuing further, still in the same direction, positive attraction is found, it shows that the vein is not ended, but if no attraction is shown, there is no indication as to the continuance of the ore.

"In crossing veins of ore from southwest to northwest, when the dip of the rock and ore is as usual to the southeast, positive attraction is first observed to come on gradually, and the northwest edge of the vein is indicated by the needle suddenly showing negative attraction just at the point of passing off it. This change of attraction will be less marked as the depth of the vein is greater, or as the strike is nearer north and south. The steadiness and continuance of the attraction is a much better indication of ore than the strength or amount of the attraction. The ore may vary in its susceptibility to the magnetic influence from impurities in its substance; it does vary according to the position in which it lies, that is according to its dip and strike; and it also varies very much according to its distance beneath the surface."

Further instructions are given in the paper from which the foregoing extract was taken, some of which follow:

"It is sufficient to say that the first examinations are made by passing over the ground with the compass in a northwest and southwest direction, at intervals of a few rods, until indications of ore are found. Then the ground should be examined more carefully by crossing the line of attraction at intervals of a few feet, and marking the points upon which observations have been made, and recording the amount of attraction. Observations with the ordinary compass should be made, and the variation of the horizontal needle be noted. In this way materials may soon be accumulated for staking out the line of attraction, or for constructing a map for study or reference.

"After sufficient exploration with the magnetic needle, it still remains to prove the value of the vein by uncovering the ore, examining its quality, measuring the size of the vein, and estimating the cost of mining and marketing it. Uncovering should first be done in trenches dug across the line of attraction, and carried quite down to the rock. When the ore is in this way proved to be of value regular mining may begin. In places where there are offsets in the ore, or where it has been subject to bends, folds, or other irregularities, so that the miner is at fault in what direction to proceed, explorations may be made with the diamond drill."

[1] Dislocation of the strata.

CHAPTER II.
HOW TO TEST FOR MINERALS.

When the mineralogist wishes to know the names of the specimen he holds in his hand, he, in the case of a mineral difficult to determine, considers all the following properties:

• Crystalline form and structure,
• Cleavage,
• Fracture,
• Tenacity,
• Hardness,
• Specific Gravity as compared with that of water,
• Luster,
• Color and Streak,
• Transparency or otherwise,
• Taste,
• Odor,
• Chemical Composition tested by analysis,
• Pyrognostic characters as determined by the use of the blowpipe,
• Mode of occurrence and associated minerals.
• Crystalline Form and Structure. Unfortunately the science of crystallography is extremely complicated and long study is necessary to master it; once acquired, however, it is of paramount usefulness to the student. According to Dana there are six systems, to one of which every crystal may be referred. They are:
  • (1) Isometric; (2) Tetragonal; (3) Hexagonal or Rhombohedral; (4) Orthorhombic; (5) Monoclinic; (6) Triclinic.

In the isometric system there are three equal axes at right angles to each other.

In the tetragonal system there are three axes at right angles to each other. Two of these are equal, while the third, or vertical angle, is longer or shorter.

There are two divisions of the hexagonal system; the hexagonal system properly so-called, and its rhombohedral division. All forms are referred to four axes, three equal axes inclined to each other at angles 60 degrees in a common horizontal plane, and a fourth vertical axis at right angles, and longer or shorter. The rhombohedral division comprises crystals having but three planes of symmetry, intersecting at angles of 120 degrees in the vertical axis. They are regarded as half forms of the corresponding hexagonal crystals.

In the orthorhombic system there are three unequal axes at right angles to each other.

In the monoclinic system there are three unequal axes, of which one, the lateral axis, is inclined to the vertical, while the angles between the others are right angles.

In the triclinic system there are three unequal axes and these intersections are all oblique. The student who wishes to pursue this subject further should consult Dana's System of Mineralogy.

Physical Mineralogy. Cleavage is the line of easiest separation in a mineral. It may be perfect, imperfect, interrupted, etc.

Fracture, referring to any surface except that of a cleavage fall, may be uneven, conchoidal (shell-like), hackly (rough), etc.

Tenacity refers to such qualities as brittle, sectile, malleable, flexible, or elastic.

Hardness is represented by the difficulty with which a smooth surface is scratched. The scale in general ore was devised by Mohs. It is:

1. Talc. Scratched by the finger nail.
2. Gypsum. Ditto, but with more difficulty. Will not scratch a copper coin.
3. Calcite. Scratched by a copper coin.
4. Fluorite. Is not scratched by a copper coin and does not scratch glass.
5. Apatite. Scratches glass, but with difficulty. Is readily scratched by a knife.
6. Feldspar. Scratches glass with ease. Is difficult to scratch by knife.
7. Quartz. Cannot be scratched by a knife and readily scratches glass.
8. Topaz. Harder.
9. Corundum. Harder.
10. Diamond. Scratches any other substance.

Hardness may be intermediate. For instance, any mineral that scratched quartz and is soft enough to be scratched by topaz, in turn would be rated at 7.5.

Specific Gravity. This is the density of mineral and other substances compared with that of water. It is particularly valuable in determining heavy metals.

To find the specific gravity of any solid body divide its weight in air by the loss of weight in water, at a temperature as near 60 degrees F. as possible, and the quotient will equal the specific gravity. In the case of gases, such as nitrogen, oxygen, etc., hydrogen is taken as the unit.

Luster. There are seven kinds of luster, viz: Metallic, the luster of metals; adamantine, that of the diamond; vitreous, of broken glass; resinous, of the yellow resins; greasy; pearly; silky. There are five degrees of intensity of luster recognized, viz: Splendent; shining; glistening; glimmering; dull.

Color and Streak. The streak is the color of the powder of the mineral when rubbed on unglazed porcelain, or scratched with a knife.

Transparency. Minerals may be transparent, sub-transparent, translucent, sub-translucent, opaque.

Taste. Minerals may be salt, bitter, sweet, etc.

Odor. This test is not of much use with most minerals until heat is applied. All the petroleum oils, however, are often detected by their odor.

Chemical Composition. This may always be determined by suitable tests with reagents.

Pyrognostic Characters. As a means of readily determining the nature of a specimen the blowpipe is unrivalled—if in the hands of one who understands it.

Mode of occurrence and associated minerals. A knowledge of these matters often assists in a determination.

A regular fire assay is not within reach of many prospectors, for the necessary apparatus cannot, as a rule, be carried in the wilderness. Whenever possible, however, a fire assay gives the truest results, especially in the case of gold and silver.

SCALE FOR WEIGHING ORE.

The operation includes testing the ore, sampling and pulverizing, weighing the ore and reagents, calcination and roasting, reduction and fusion, distillation and sublimation, scorification and cupellation, inquartation and parting the gold and silver, weighing and tabulating. "Notes on Assaying" by Dr. Ricketts is a very useful manual to have at hand.

A TOLERABLY COMPLETE OUTFIT INCLUDES:

A pair of scales for weighing ore and buttons of base metal. It should take 10 ounces in each pan, and show 1/20 of a grain.

A bullion scale to be kept strictly for the precious metals. Loaded with one gramme, it should show 1/20 of a milligramme.

ASSAY BALANCE FOR BULLION.

Weights. Avoirdupois; troy, metric and "assay." Assay weights save much calculation. The unit of the system is a weight of 29.166 grammes. Its derivation is as follows:

2000 lbs. : 1 A.T. :: 1 oz. Troy : 1 milligramme.

To use this system, weigh out one A.T. of the ore and whatever number of milligrammes of gold and silver the assay gives indicates an equal number of Troy ounces to the ton of 2000 lbs. Avoirdupois.

A muffle and a melting furnace, portable and of medium size, are handy, though furnaces may be built of ordinary brick, lined with fire brick, that would be better for permanent use.

The fuels may be coke, anthracite or bituminous coal, charcoal, oil or gas.

ASSAY FURNACE.
PORTABLE ASSAY FURNACE.

Crucibles of black lead, French clay, Hessian sand, and quicklime are necessary to hold the assay.

CRUCIBLES.

SCORIFIER.
STEEL CUPEL MOULD.

Roasting dishes, scorifiers and cupels are required. The cupel is made of the ashes of burnt bone, and it is better to make them on the spot, as the bone ash may be carried anywhere without damage, whereas the cupels are very fragile. The bone ash is moistened with water, stamped in a cupel mould, and allowed to dry slowly. A good one will absorb its own weight of lead, but it is better to calculate on its absorbing but three-quarters of that amount.

SCORIFICATION FURNACE.

SCORIFICATION MOULD.

The crucible, scorification and cupel tongs, a couple of hammers, iron pestle and mortar, sieves from 20 to 100 mesh, and scorification mould complete the requisite tools.

HAMMER.

HORN SPOON.

STEEL MORTAR. ALCOHOL LAMP.

In addition, however, the assayer will require quite a bulky lot of apparatus, reagents and chemicals. All dealers keep lists of assayers' supplies on hand, and a full and complete assortment will cost about $200 in New York or Chicago. Quart bottles, with glass stoppers; ordinary corked bottles, ring stands, alcohol lamps, wash bottles, test tubes, horn spoons, iron pans, parting flasks, annealing cups, glazed black paper—these will suffice, provided the assayer has, as well, the outfit recommended for blow-pipe work.

TEST TUBE.

Dry reagents, such as litharge, borax (crystallized), silica, cyanide of potassium, yellow prussiate of potash, argol, charcoal, starch, metallic iron, pure lead, nitre, powdered lime, sulphur, carbonate of ammonia and common salt are necessary. As solvents and precipitants, distilled water, sulphuric, nitric and hydrochloric acids, chloride of sodium, nitrate of silver and sulphuretted hydrogen are also indispensable.

This will seem rather a formidable list, and so, under certain conditions, it may be; indeed, where means of transport is limited, all regular assay work must be postponed until the return to civilization. Assaying is not, however, difficult, being mostly a matter of rule of thumb, and correct results may be arrived at without a deep knowledge of chemistry, although such knowledge will never come amiss.

A preliminary examination will show what the ore probably is. The blow-pipe is especially useful, though to the skilled assayer often unnecessary. The ore is first powdered, and any metallic flakes picked out and tested separately. A fair sample must be selected, otherwise all the work will be thrown away and the result be valueless.

The next step is weighing the ore and the reagents. Moisture is drawn off by heating in a crucible, a low heat being sufficient. Roasting will eliminate sulphur, antimony, arsenic, etc., and must take place in a flat dish, so that the air may have free access. The powder should be stirred frequently.

Reduction is the operation of removing oxygen, and it takes place usually in a crucible or scorifier.

Scorification consists in placing the ore in an open dish with proper reagents, and collecting all the volatile ingredients in the slag. Cupellation, on the other hand, collects them in the bone ash, of which the cupel is composed.

When silver must be separated from gold, it is sometimes convenient to increase its proportion by the addition of some known weight of the inferior metal. After fusing, the globule is placed in nitric acid, and the silver parted from the gold, which may then be weighed. This result subtracted from the weight of the original globule gives the amount of silver.

To test an ore for gold, take a pound of it, crush in mortar and pass through a fine sieve. Take one-fourth ounce Troy of the powder. Place in scorifier with an equal amount of litharge. Cover with borax that has been melted and powdered, and put the scorifier in the muffle of the furnace. A blacksmith's forge might do at a pinch. Heat until the mass has become a fluid, possibly twenty or thirty minutes. Next pour into the scorification mould, and, after the slag has set, remove it with a hammer. Hammer the button into a cube and place it in the cupel, which must first have been thoroughly heated. Heat until all the base metal has been absorbed by the cupel and the button has "brightened," or flashed; when this occurs, remove the cupel to the front of the muffle, cool, and remove the button with pincers. Weigh it, and you have the amount of gold and silver in ¼-ounce Troy. A simple sum in proportion gives the amount in a ton.

All ores containing sulphur, arsenic, antimony, or zinc, should be roasted.

There are three stages in the scorification process; roasting, fusion, and scorification. During the first, the heat should be moderate until fumes cease to be given off; during the second, the heat is raised and a play of colors is seen on the surface of the lead; in the closing stage, the heat is lowered for a time until the slag covers the lead, when it is again raised for a short time and the scorifier removed. Brittle buttons may be due to arsenic, antimony, zinc or litharge, and must be re-scorified before cupellation, with more lead.

Take the cupel slowly from the fire to avoid "spitting," by which portions of the buttons are lost. Watch closely for the brightening.

Silver is volatile at a high heat, but when the muffle is almost white, the metal well fused and clean, the fumes rising slowly, and the cupel a cherry red, all is going smoothly. If the fumes rise rapidly, the muffle is too hot. On the other hand, dense, falling fumes show the temperature is too low. Lead that is poor in silver stands the highest heat without vitiating the assay.

When the material in the cupel "freezes," i.e., the absorption by the cupel stops, reject the assay and try again, giving more heat or more lead.

Gold. Practically, the metal most prospectors seek is gold. It is so enormously valuable and constitutes so very small a percentage of any ore, that care must be taken or it may escape detection and be lost. Panning is the miner's method. He crushes his ore thoroughly, and places it in the pan with water; then, with a motion easy to learn but difficult to describe, he swirls the water around, allowing a little of it to escape at each revolution, carrying with it the rubbish, until finally he has a little black sand and perhaps a few grains of yellow substance, which is gold. Mica, or fool's gold, puzzles nobody but the ignoramus. True, it looks like gold in certain positions and lights, but gold will beat out thin under the hammer, just as lead would, while mica will break up into a floury powder. Mica is very light, while gold is very heavy; so there is no excuse for confounding the two. If an ore contains sulphurets and gold, the latter may be coated with some sulphur or arsenic, which would prevent the gold from amalgamating. The only remedy for this is roasting. No single acid will dissolve gold, but a solution known as aqua regia, made up of three parts of hydrochloric acid and one part of nitric acid, dissolves it. If to the solution so obtained you add some sulphate of iron, you will get a precipitate which is metallic gold, although it does not look like it, as it is brown in color; but if you place this precipitate in a crucible and heat, you will get a yellow bead of pure gold. Another test for gold is to take the solution as above obtained and add thereto a solution of chloride of tin, when you obtain a purple coloration that has been called the purple of Cassius.

Gold may be distinguished from all other metals by the three following tests: It is yellow; it may be flattened by the hammer; it is not acted upon by nitric acid.

Pure gold is soft, and the point of a knife will scratch it deeply. Pounded in a mortar, the pulverized mineral should be passed through a cheese-cloth screen stretched over a loop of wood. If the course contains much pyrite, it must be roasted before washing in the pan and amalgamating. Sample well, weigh out two pounds, put it in a black iron pan, with four ounces of mercury, four ounces of salt, four ounces of soda and a half gallon of boiling water. Stir with a green stick, and agitate until the mercury has been able to reach all the gold. Pan off into another dish so as to lose no mercury, squeeze the amalgam through chamois leather or new calico previously wetted. The pill of hard amalgam may be placed on a shovel over the fire or in a clay tobacco pipe and retorted.

Gold is readily acted upon by the mixture of nitric and hydrochloric acids known as aqua regia, or by any solution producing chlorine. Some of the mixtures which attack it are bisulphate of soda, nitrate of soda and common salt, hydrochloric acid and potassium chlorate, and bleaching powder. The action is more rapid in hot than in cold solutions, and impure gold is more easily dissolved than pure.

Mercury dissolves gold rapidly at ordinary temperatures, the amalgam being solid, pasty or liquid. Gold rubbed with mercury is immediately penetrated by it. An amalgam containing 90 per cent. of mercury is liquid; 87.5 per cent., pasty; 85 per cent., crystalline. These amalgams heated gradually to a bright red heat lose all their mercury, and hardly any gold. About one-tenth of 1 per cent. of mercury remains in the gold until it is refined by melting.

The veins from which the gold of the world is won do not, on an average, hold the precious metal in greater proportion than one part of gold in 70,000 parts of veinstone. Under favorable conditions a proportion not one-fifth as rich as this, may yield a rich return. In hydraulic mining on a large scale, one part of gold in 15,000,000 parts of gravel has paid a dividend.

A test known as Darton's is believed to be a valuable means of detecting minute quantities of gold in rocks, ore tailings, etc.

"Small parts are chipped from all the sides of a mass of rock, amounting in all to about ¼ ounce. This is powdered in a steel mortar and well mixed. About half is placed in a capacious test tube, and then the tube is partly filled with a solution made by dissolving 20 gr. of iodine and 30 gr. of iodide of potassium, in about 1½ ounces water. The mixture thus formed is shaken and warmed. After all particles have subsided, dip a piece of fine white filter paper in it; allow it to remain for a moment; then let it drain, and dry it over the spirit lamp. It is next placed upon a piece of platinum foil held in a pincers, and heated to redness over the flame. The paper is speedily consumed; and after again heating to burn off all carbon, it is allowed to cool and is then examined. If at all purple, gold is present in the ore, and the relative amount may be approximately deduced. This method takes little time, and is trustworthy."

Black sand, which is iron, often with some platinum and iridium, sometimes interferes with the result of a gold assay. Attwood recommends the following method as applicable to such a case:

"Take 100 to 1000 grains and attack with aqua regia in a flask; cool for about thirty minutes or more; dilute with water and filter. If gold is present, it will now be held in solution in the filtrate. Remove the filter and evaporate the filtrates to dryness; then add a little hydrochloric acid, evaporate and re-dissolve the dry salt in warm water; add to the solution so formed proto-sulphate of iron; which will throw down the gold in the form of a fine, dark precipitate. The precipitate is seldom fine, being mixed with oxides of iron, and must now be dried in the filter paper, and both burned over the lamp in a porcelain dish. Then mix the dried precipitate with three times its weight of lead; fuse, scorify and cupel. In case platinum, iridium, etc., are found associated with the gold, an extra amount of fine silver should be added before cupellation, and the gold button will be found pure."

In one of his reports the State Mineralogist of California gives a most lucid description of a mechanical assay of gold-bearing sands, stamped ore, etc., etc. He states:

"It must be understood that this is only a working test. It does not give all the gold in the rock, as shown by a careful fire assay, but what is of equal importance to the mine-owner, mill-man, and practical miner, it gives what he can reasonably expect to save in a good quartz mill. It is really milling on a small scale. It is generally very correct and reliable, if a quantity of material be sampled. The only operation which requires much skill is the washing, generally well understood by those who are most likely to avail themselves of the instructions. These rules apply equally to placer gravels. Take a quantity of the ore—the larger the better—and break it into egg-sized pieces. Spread on a good floor, and with a shovel mix very thoroughly; then shovel into three piles, placing one shovelful upon each in succession until all is disposed of. Two of the piles may then be put into bags. The remaining pile is spread on the floor, mixed as before, and shovelled in the same manner into three piles. This is repeated according to the quantity sampled, until the last pile does not contain more than 30 pounds of ore. As the quantity on the floor becomes smaller, the lumps must be broken finer until at last they should not exceed one inch in diameter. The remainder is reduced by a hammer and iron ring to the size of peas. The whole 30 pounds is then spread out, and after careful mixing portions are lifted with a flat knife, taking up the fine dust with the larger fragments, until about 10 pounds have been gathered. This quantity is then ground down fine with the muller, and passed through a 40-mesh sieve. If the rock is rich, the last portion will be found to contain some free gold in flattened discs, which will not pass this sieve. These must be placed with the pulverized ore, and the whole thoroughly mixed, if the quantity is small, but if large must be treated separately, and the amount of gold allotted to the whole 10 pounds and noted when the final calculation is made.

"From the thoroughly-mixed sample, two kilogrammes (2000 grammes) must be carefully laid out. This is placed in a pan or, better, in a batea, and carefully washed down until the gold begins to appear. Clean water is then used, and, when the pan and the small residue are cleaned, most of the water is poured off and a globule of pure mercury (which must be free from gold) is dropped in, a piece of cyanide of potassium being added with it. As the cyanide dissolves, a rotary motion is given the dish, best done by holding the arms stiff and moving the body. As the mercury rolls over and ploughs through the sand, under the influence of the cyanide it will collect together all the particles of free gold. When it is certain that all is collected, the mercury may be carefully transferred to a small porcelain cup or test tube, and boiled with strong nitric acid, which must be pure. When the mercury is all dissolved the acid is poured off, more nitric acid applied cold, and rejected, and the gold is then washed with distilled water and dried.

"The object of washing with acid the second time is to remove any nitrate of mercury which might remain with the gold, and which is immediately precipitated if water is first used.

"The resulting gold is not pure, but has the composition of the natural alloy. Before accurate calculations of value are possible, the gold must be obtained pure and weighed carefully. To purify the gold it should be melted with silver, rolled out or hammered thin, boiled twice with nitric acid, washed, dried, and heated to redness.

"The method of calculating this assay is simple. It will be observed that 2000 grammes represent a ton of 2000 pounds; then each gramme will be the equivalent of one pound avoirdupois, or one 2000th part of the whole, and the decimals of a gramme to the decimals of a pound. Suppose the ore yielded by the assay just described, fine gold weighing .072 gramme, it must be quite evident that a ton of the ore would yield the same decimal of one pound. Now one pound of gold is worth $301.46, and it is only necessary to multiply this value by the weight of gold obtained in grammes and decimals to find the value of the gold in a ton of ore—$301.46 × .072—$21.70. The cyanide solution should be kept rather weak, as gold is slightly soluble in strong solutions of cyanide of potassium. Cyanide is a deadly poison."

Touchstones are useful in deciding the probable value of gold alloys. Several pieces of the metal under examination are cut with a cold chisel, and the fresh edges drawn over the touchstone. These streaks are touched with nitric acid on a glass rod. Should no reaction follow, the gold is at least 640 fine. Wipe the stone with soft linen and try with test acid, made by mixing 98 parts of chemically pure nitric acid with two parts of hydrochloric acid, adding 25 parts distilled water by measure. If this has no effect, take a touch needle marked 700, and make a similar streak on the stone samples. Compare, and, if necessary, continue with the other needles, using a higher number each time. An approximate estimate of the sample will soon be obtained. Should the gold seem poorer than 640 fine, try with the copper or silver needle. Practice and a good eye soon make this method very certain in its results.

Retorted amalgam is likely to contain mercury. To test for it, put a small fragment into a closed glass tube, taking care that it falls quite to the bottom. Heat the gold over a spirit lamp, and a deposit of mercury will soon be seen upon the colder sides of the tube above the bottom. The tube may be broken and the mercury collected into a globule under water.

In mining regions gold dust passes current as coin, according to what is supposed to be its value. Occasionally counterfeit dust is offered. The readiest means by which it may be detected are as follows: The dust from any one district is always much alike, and any unusual appearance should create suspicion. Try any doubtful pieces on a small anvil, remembering that gold is extremely malleable. Test some of the gold with nitric acid; effervescence or evolution of red fumes, or coloration of the acid prove impurities to be present. Place two watch-glasses (most useful in chemical tests) on paper; the one on a white sheet, the other on a black, and with a glass rod convey a few drops of nitric acid from the dish to each. To the glass on white paper add a drop or two of ammonia; a blue color would indicate copper. To the other add hydrochloric acid; should a white precipitate form, it proves silver. If no action is noticed, even after heating the dish, the dust is genuine. As "dust" is sometimes merely copper coated with gold, the better plan is to cut all the larger grains in two, so that the acid may attack the copper should it be present.

Copper. Copper is a very easy mineral to test for. First crush the ore and dissolve it in nitric acid by heating. Then dilute with some water, and add ammonia. The solution should turn dark blue. The carbonate ores of copper do not extend deep in the mine. Their places are taken by copper pyrites. Sulphide ores are usually difficult to treat, and when they are to be tested it is better to roast them before trying the tests for color.

Test for copper may also be made as follows:

The sample must be pulverized. Take an ounce of the powder, and place in a porcelain cup. Add forty drops of nitric acid, twenty drops of sulphuric acid and twelve drops of hydrochloric acid. Boil over the spirit lamp until white fumes arise. When cool, mix with a little water. Filter and add a nail or two to the liquid. The copper will be precipitated, and may be gathered up and weighed. The amount of copper in the sample multiplied by 32,000 will be the copper in a ton of the ore.

Should copper be suspected, roast the powdered ore and mix with an equal quantity of salt and candle grease or other fat; then cast into the fire, and the characteristic flame of copper—first blue and then green—will appear. This test is better made at night.

Coal. Coal is often more valuable than gold, and the prospector should be prepared to estimate the value of any seams he may come across during his travels. The following is a very rough but wonderfully effective test for coal. Take a clay pipe, pulverize your sample, weigh off twenty pennyweights, and place it in the bowl of the pipe. Make a cover with some damp clay. Dry thoroughly, and put the bowl upside down over a flame. The gas in the coal will come out through the stem, and may be lit with a match. Let the pipe cool after the gas has all escaped, break off the covering of clay, and if the coal was adapted for coke the result will be a lump of that substance in the bowl. Weigh this. The difference in weight between the coke and the twenty pennyweights of coal that were placed in the bowl will represent the combustible matter forced out by the heat. Now take this coke and burn it on a porcelain dish over the lamp. You will have more or less ash left, and the difference in weight of the ash and the coke will be the amount of fixed carbon in the coal. Your test is complete, and it need not have cost you even the pipe. Sulphur is a detriment to coal, and if you notice much of it in the escaping fumes, you may be sure your sample is not worth much.

Mercury. Cinnabar, the common ore of mercury, is a sulphide. Scratch it with a knife, and the streak will be bright crimson. Dissolve the ore in nitric acid, add a solution of caustic potash, and you have a yellow precipitate. A very pretty test is to place the ore pulverized in a glass tube with some chloride of lime; close the top of the tube, and place a smaller one therein, so bent that it will pass into a basin of water; heat the bottom of the tube containing the ore and lime, keeping the upper part and the small tube cold with wet rags, and you will have a deposit of quicksilver in the basin.

Silver. Silver ore may be detected by dissolving a small quantity in a test tube with a few drops of nitric acid. Boil until all the red fumes disappear. Let the solution cool, and add a little water. Filter the whole, and add a few drops of muriatic acid, which will precipitate the white chloride of silver. Dissolve this precipitate with ammonia; then add nitric acid once more. Exposed to the light, the precipitate soon shows a violet tint. Pure silver is the brightest of metals, of a brilliant white hue, with rich luster. To detect chloride of silver in a pulp, rub harshly with a clean, bright and wet copper cartridge or coin, and if there be silver in the pulp the copper will be coated with it. Graphite will also whiten copper, but the film is easily rubbed off.

Nickel. Nickel may be determined as follows: A little of the powdered ore taken up on the point of a penknife, and dissolved in a mixture of ten drops of nitric and five drops of muriatic acid, should be boiled over a lamp for a few minutes, and ten or twelve drops of water added. A small quantity of ferrocyanide of potash will throw down a whitish-green precipitate, indicating nickel.

Platinum. Platinum is a most refractory metal to treat, as it must be boiled for at least two hours in the mixture of muriatic and nitric acid, known as aqua regia. A small amount of alcohol is to be added to the solution, and the latter filtered. The platinum is precipitated with ammonia chloride.

Manganese. Manganese may be proved as follows: A few grains of powdered ore are placed in a test-tube, with three or four drops of sulphuric acid. Two or three grains of granulated lead or litharge being dropped in, the color will become pink should manganese be in the ore.

A preliminary examination of a mineral may be made with a pocket lens and a penknife. With the first, any conspicuous constituents may be recognized, while a scratch with the point of the latter will give an idea as to the softness or hardness of the mineral. Should much quartz (silica) be present, a sharp blow with the steel will cause sparks.

The next test should be with some ore powdered and held over a spirit flame. A drop or two of water and a drop of sulpho-cyanide of potash will reveal iron, should such be present, by a deep red coloration.

To another portion add one drop of hydrochloric acid, and a dense, curdy precipitate will indicate silver, if there be any.

Added to the same original nitric acid solution, several drops of ammonia water would detect copper by a blue color.

Antimony, tin, aluminum, zinc, cobalt and nickel, uranium and titanium are best shown by the blowpipe.

Carbonates, that is those minerals that contain carbon and oxygen in addition to the metal, effervesce when brought into contact with hydrochloric acid. Some sandstones have a small amount of lime carbonate, and must be tried under the lens, as the bubbles are microscopic. These tests are extremely useful, but by no means infallible, owing to so few ores being pure.

When the explorer wishes to know all the constituents of the ore he has found, he must analyze it. An analysis gives every substance in the ore. Such examinations may be either by the "dry" or "wet" methods, though usually the term "analysis" is restricted to the latter, and "fire assay" is used to describe the former. The wet assay for silver, lead or mercury is effected as follows:

Drop a little powdered ore in a test tube; add nitric acid; dilute with 1/8 water; warm gently over the spirit lamp. It may dissolve or it may not. In the latter case, add four times as much hydrochloric acid. Should all these attempts fail, a fresh sample must be taken, and equal parts of sodium carbonate and potassium carbonate added, and the whole strongly heated in a platinum crucible. The contents, after cooling, is dissolved in dilute nitric acid.

In any case the assay will now be dissolved, and will be in the solution. Filter. Pour ten drops into a test tube; add three or four drops of hydrochloric acid. A precipitate appears. It may be silver, lead or mercury. If silver, it grows dark violet after exposure to sunlight, or 30 or 40 drops of ammonia dissolves it in a few moments. Should it not dissolve, it is lead or mercury. Test for lead by filtering, and heating some of the precipitate on charcoal before the blow-pipe. A bead and yellow incrustation indicate lead. Should none of these things happen, then the metal is mercury. Filter; place in glass tubes; heat gently, and a mirror of quicksilver will appear on the sides of the glass.

This is as far as the prospector, without the various reagents and chemicals that the analyst has always at hand, will be able to go. More complex treatment must be reserved until a return to civilization.

CHAPTER III.
BLOW-PIPE TESTS.

BLOW-PIPE.

As a means of readily detecting the presence of minerals in their ores the blow-pipe, in the hands of a skillful operator, is unrivaled. Nor is this skill at all hard to come by; two or three weeks' patient study under a good master should teach a great deal, and subsequently proficiency would come by practice in the field. Unfortunately, some very clever men have become so enthusiastic as to blow-pipe work that they have devised methods by which the amount of metal in an ore as well as its nature may be determined, but in so doing have so enlarged the amount of apparatus, and complicated the tests so seriously that the simplicity of the blow-pipe outfit is in danger of being lost, and its chief advantage of being forgotten; for there are many better ways of determining the value of an ore. A good assay or, better still, a mill run, is worth incomparably more than any quantitative blow-pipe test, even when conducted by a Plattner.

The chemical blow-pipe is made of brass or German silver, with platinum tip.

The best fuel, taking everything into consideration, is a paraffin candle in cold climates, and a stearine candle in hot ones. Tallow may do in an emergency, but it requires too much snuffing.

REDUCING FLAME.

The blow-pipe can produce two flames. The one known as the reducing flame, and generally printed as R.F.; and the oxidizing flame, represented by the initials O.F. In the first the substance under examination is heated out of contact with the air and parts with its oxygen. In the second, it is heated in the air and absorbs oxygen.

OXIDIZING FLAME.

Well-burnt pine or willow charcoal in slabs 3 inches by 1¾ inches is the material upon which the mineral to be tested is placed. A small shallow depression is scraped out of one side of it and the assay placed therein.

Platinum wire, some 3 inches long, conveniently fused into a piece of glass tube as a handle, is used to test the coloration of minerals in the flame. This should be cleaned occasionally in dilute sulphuric acid and then washed in water.

A small pair of forceps with platinum points serve a great variety of purposes, but the beginner must be careful not to heat metallic substances in them to a red heat, as he may thereby cause an alloy of the metal with the platinum and spoil them for future use.

AGATE MORTAR.

Glass tubing one-twelfth to one-quarter inch in diameter and from four to six inches in length is used for a variety of purposes. From this material what are known as closed tubes may be made by heating a piece of the tubing at or about its center over a spirit lamp, and, when the glass has fused, pulling it apart. These closed tubes are used in heating substances out of contact with the air.

A small agate mortar is indispensable. It must be used for grinding substances softer than itself to a powder, but it will break if rapped sharply.

A small jeweler's hammer is used to flatten metallic globules upon any hard surface A regular blow-pipe outfit would include a small anvil for this purpose, but it is hardly necessary, as any iron or steel surface will do.

MAGNET. LENS. NEST OF TEST TUBES.

A magnet will detect the presence of any magnetic mineral, especially if it is reduced to powder and the test made under water.

Two small files, one three-cornered and the other rat-tailed, must be included in the list of requisites. By means of the former, glass tubing may be notched and pulled or pushed apart, and the latter is necessary in fitting glass tubing to the cork of wash-bottles and other apparatus.

A good lens is indispensable. That known as the Coddington is as good as any.

A dozen test tubes of hard glass, with stand, in small and medium sizes, should not be forgotten.

A glass funnel 2½ inches in diameter is requisite in filtering. The circular filter papers are folded in four and placed in the funnel, point down, three thicknesses of the paper being on one side of the funnel and one thickness on the other.

A wash-bottle is made from a flask into which a sound cork has been placed with holes in it for two pieces of glass tubing. The one serves as a mouth-piece into which the operator blows, while the other, reaching almost to the bottom of the bottle and ending in a spout outside the cork, permits a stream of water to be forced out of the bottle when it is blown into.

A few glass rods in short lengths do for stirrers. A little ingenuity is better than much apparatus.

Of reagents, all those to be found in a well-appointed laboratory may occasionally be of service, but the rough and ready prospector can get along fairly well with the following: Carbonate of soda, borax, microcosmic salt, cobalt solution, cyanide of potassium, lead granulated, bone ash, test papers of blue litmus and turmeric, the former for proving the presence of acid in a solution and the latter that of an alkali.

The foregoing are all dry reagents. Among the wet reagents are: Water—clean rainwater—or, better still, distilled water; hydrochloric acid, sulphuric acid, nitric acid, ammonia, nitrate of cobalt.

Heating a mineral with carbonate of soda on charcoal is accomplished as follows: The pulverized mineral, intimately mixed with three times its bulk of carbonate of soda, is placed in the cavity on the coal. Tin ore, which is very difficult to reduce, should have a fragment of cyanide of potassium placed upon it after it has been heated for a few seconds, and the flame is then reapplied. A globule of metal should result, and perhaps an incrustation on the coal. The reaction is as follows:

A small loop is made at the end of the platinum wire, and it is heated and dipped in borax; heated again, then touched while hot to the powdered mineral and heated once more. The following colors are obtained:

COLOR OF BEAD.

The substance to be tested is generally powdered and moistened, placed in the cavity and covered or not as circumstances may demand, with a pinch of carbonate of soda or other suitable reagent. The following results may be obtained:

Antimony. Place the mineral in the cavity with a little of carbonate of soda, and blow upon it with the inner or oxidizing flame. This is formed by inserting the blow-pipe an eighth of an inch into the flame and blowing steadily. A white incrustation on the coal, and a brittle button of antimony should be the result.

Lead. Treat the suspected lead ore the same way, and you will get a yellow incrustation on the coal and a button of malleable lead.

Zinc. Proceed as above, and after blowing for a few seconds moisten the incrustation with a drop of nitrate of cobalt. Heat once more, but this time use the outer or reducing flame, which is produced by keeping the point of the blow-pipe a little outside the flame and blowing more gently than before, so that the whole flame playing upon the coal may be yellow in color. A green incrustation will be an evidence of zinc.

Copper. As usual, mix the ore and the soda into a paste and fuse it with the oxidizing flame. Dig the mass out of the charcoal with the point of a knife and rub it in the mortar with water. Now decant into a test tube, and, allowing the sediment to settle, pour off the water. If there was copper in the ore, red scales will be found in the test tube.

Arsenic. Heat in the inner flame for a second or two, and if the ore contains arsenic you will notice an odor of garlic.

Tin. This is a very difficult ore to reduce, but the addition of a little cyanide of potash to the powdered ore will make it easier. Fuse, after moistening on the charcoal, in the oxidizing flame, and you will probably obtain small globules of tin.

Silver. Make a paste of the ore with carbonate of soda; add a small piece of lead and fuse into a button. Make a second paste of bone ash and water, and after you have dried it with a gentle flame place the button of silver and lead on the bone ash, and turn on the oxidizing flame. The lead will disappear, leaving a silver globule. Should it not be pure white, but more or less tinged with yellow, it probably contains gold; and if the button be dissolved in nitric acid, whatever remains behind is gold.

Sometimes it is desirable to determine whether tellurium is present in an ore. This is very easy to find out. All that is required is a blow-pipe, alcohol lamp and a porcelain dish. Break off a small piece of the ore, place it in the dish previously warmed, blow upon the ore with the blow-pipe until it is oxidized, then drop a little sulphuric acid on the ore and dish. If tellurium be present, carmine and purple colors on the assay will proclaim the fact.

Bismuth ores are very heavy; usually they have more or less antimony associated with them, which is a drawback, as the separation is an expensive matter and the returns are less than they would be from a low grade pure ore. In testing for this metal, dissolve a crushed sample in nitric acid and then add potash in excess. If the ore is one containing bismuth, you should have a white precipitate; if it contains cobalt, you will get a bluish-green coloration. Bismuth is worth about fifty cents a pound if pure and free from antimony.

Galena is often mistaken for other ores, specular iron ore for instance. If the ore be crushed and heated in nitric acid until dissolved, some water added, and an addition made to the solution of a few drops of ferrocyanide of potassium, a dark blood-red precipitate is thrown down. If the ore were galena, there would be no coloration. The so-called steel galena which carries a little zinc is generally richer in silver than the ordinary cube galena, though the reverse is sometimes the case.

If lead ore be dissolved in nitric acid, the solution diluted, and some hydrochloric acid added, a white precipitate is thrown down. Add ammonia and the precipitate remains unaltered.

The blow-pipe operator has to learn to breathe and blow at the same time; the breathing he does through the nostrils, the blowing is produced by the natural tendency of the cheeks to collapse when distended with air. A skillful operator can blow for many minutes at a time without the slightest fatigue.

To identify cinnabar, the ore from which quicksilver is obtained, make a paste of the substance in powder and carbonate of soda. Heat in the open tube, and a globule of mercury will result.

Sulphur turns silver black. Make a paste with carbonate of soda, heat on the charcoal, and removing the mass with the point of a knife lay it on a silver coin and moisten. A black sulphide of silver should show quickly on the coin if sulphur is present. Magnesia gives a faint pink color when heated and treated with nitrate of cobalt on coal. Alumina under the same circumstances give a blue color.

Roasting is an oxidizing process, the substance being heated in air, so that it may absorb oxygen.

The test by reduction with soda on coal in the R.F. is particularly valuable in the case of copper ore, as little as 1 per cent. being detected.

CHAPTER IV.
ECONOMIC ORES AND MINERALS.

Aluminum is derived from two ores, cryolite and bauxite. This metal has made rapid strides into favor during the past half-dozen years. Although known since 1827, it remained a rare substance in the metallic form, though it is the most abundant of any of the metals in its ore. In ordinary clay there is an inexhaustible source of aluminum. But the ores that yield the metal cheaply are few. Until recently, cryolite, found abundantly in Greenland, was the chief source of the metal, but now bauxite is used in its place. Bauxite is a limonite iron ore in which a part of the iron has been replaced by aluminum. It is found in Alabama, Georgia and Arkansas, as well as in Europe. Aluminum is white, and very light in weight. It does not tarnish easily.

The chemical composition of these ores is:

In 1895 the production of this metal in the United States was 900,000 pounds. In 1899 it rose to 6,500,000 pounds. The only firm producing aluminum is the Pittsburg Manufacturing Company of Buffalo, N.Y., who reduce the metal from bauxite, which they obtain in the southern states. One of the latest uses for this metal is for gold miners' pans. The French seem to keep ahead of the rest of the world in finding new uses for aluminum.

Most of the supply of cryolite comes from Greenland, where it occurs in veins running through gneiss rocks. Glass-makers use it and pay good prices for it. Lately makers of aluminum also buy it, as it contains 13 per cent. of that metal.

A new aluminum-bearing mineral, discovered in New Mexico and in Ohio, is called native alum. It gives 50.16 per cent. alumina, and may be treated by solution in warm water, filtration, evaporation and roasting. No estimate has yet been made of the amount available.

As bauxite promises to be in greater demand in the future than in the present, owing to the ever-increasing demand for aluminum, the prospector will do well to make himself thoroughly familiar with its appearance. It is creamy white when free from iron, and the grains are like little peas, or pisolitic. It contains water, aluminum, silica, and generally iron. The French beds near the town of Baux are 30 miles long and 40 feet thick. In the United States, beds have been found in Alabama, Georgia and Arkansas. The Georgia beds are turning out three-fifths of the bauxite produced in America. The ore is in beds and pockets, and enough has been prospected to assure a supply for some years to come, unless the demand should grow very decidedly, in which case a scarcity might soon be felt. The American ore is easier to work than the French, and manufacturers prefer it to any they can import, even though the cost is higher and the percentage of aluminum smaller. The Arkansas deposits are as thick as the French, and only 300 feet above the level of the tide. Imported bauxite cost $5 to $7 a ton in New York City. American ore costs $5 to $12 a long ton. Best selected Georgia brings $10.

Should the deposits of bauxite give out, the manufacturers of aluminum would probably fall back on cryolite. At Tvigtuk, on the west coast of Greenland, it exists, as a very heavy vein, in gneiss. It is semitransparent, and snow-white. Impurities may stain it yellow or red or even black. Its specific gravity is 2.95, and its hardness 2.5 to 3. It is fusible in the flame of a candle, and yields hydrofluoric acid if treated with sulphuric acid. It is still used for making soda and aluminum salts, and an imitation porcelain. It is also in general use as a flux.

Amber. This is a fossil resin, or gum, and may often be found in lignite beds. Recent discoveries have been made on the coast of British Columbia that are expected to supply the world. All pipe-smokers know it.

Antimony. The commercial ore of this metal is the sulphide known as stibnite, or gray antimony. Its composition when pure is 72 per cent. antimony and 28 per cent. sulphur. Hardness is 2; gravity, 4.5; luster, metallic; opaque; gray; cleavage, perfect. Fracture, conchoidal. Texture, granular to massive. The ore tarnishes quickly, is easily melted, or dissolved in hydrochloric acid. The associated minerals are generally the ores of lead, zinc, and carbonate of iron. Baryta may be the gangue or veinstone. Antimony is worth from 10 to 15 cents a pound.

Although antimony occurs in many minerals, the only commercial source is the sulphide, stibnite. Antimony is used as an alloy in type metal, pewter, and babbitt metals. It is injurious to copper, even one-tenth of one per cent. reducing the value of that metal very considerably. The price varies greatly, being now about 10 cents a pound.

The composition of stibnite is:

The production of antimony in this country is not very large. The output of 1899 was but 1,250 tons, valued at $241,250. The ore is worth from $40 to $50 a ton delivered at Staten Island, N.Y.