78.—Zincite.
Occurs in foliated masses or grains, powder orange-yellow; brittle; dissolves in acids without effervescence; gravity 5.5.
Value.—Yields seventy-five per cent. of zinc.
Localities.—Found in limestone with Franklinite, Garnet, etc. Sterling Hill and Mine Hill, N. J.
CHAPTER IV.
PROSPECTING FOR DIAMONDS, GOLD, SILVER, COPPER, LEAD AND IRON.
MINERAL RICHES, HOW DISCOVERED—INDICATIONS—SEARCHING FOR DIAMONDS, AND HOW TO DISTINGUISH THEM—PAYING LOCALITIES OF GOLD—“FOOL’S GOLD”—PROSPECTING FOR SILVER AND COPPER—WHERE TO LOOK FOR LEAD AND IRON.
THE mineral riches of a country are frequently discovered by attentively observing the fragments brought down by the action of water from the hills into the valleys; and on tracing these to their several sources, the veins from which they were originally detached, are in many instances found. Water also acts in another way a very important part in the discovery of mineral veins, as by closely examining the faces of the different gullies and ravines, which intersect a country, a ready means is afforded of ascertaining whether its strata are traversed by metalliferous deposits; and, therefore, in exploring with a view to its mineral productions, no opportunity should be lost of observing the various sections thus naturally laid bare.
When fragments of an ore are found on a hill-side, it is very evident that the vein must lie higher up. If the vein is horizontal and the fragments are found on the top of the hill, there is no probability of finding much if any of the vein, for generally it has been washed away. Ore-veins, however, are almost always nearly vertical; so that boring is of little use, as it might pass by the richest vein, or, striking it lengthwise, give a too favorable result.
As heavy minerals do not drift far, metals are always found near their source.
Horizontal beds can be worked at the least cost.
Pockets and nodules, or any detached masses of minerals, are soon exhausted. Veins, lodes and beds are most valuable.
Boring a three-inch hole, which costs about $1 a foot, is a good method of testing a mineral vein or bed which lies more or less horizontally. A shaft may be sunk in sandstone for from $6 to $3 per cubic yard; in slate and gravel, at from $2 to $1.
The existence of mineral springs, and the rapid melting of the snow in any locality, are no indications of ores.
Searching for Diamonds.—Few things are so unpromising and unattractive as gems in their native state. Hence their slow discovery. There is little doubt that diamonds exist in many places as yet unknown, or where their presence is unsuspected. It is very difficult for the unpracticed eye to distinguish them from crystals of quartz or topaz. The color constitutes the main difficulty in detecting their presence. They are of various shades of yellowish brown, green, blue and rose-red, and thus closely resemble the common gravel by which they are surrounded. Often they are not unlike a lump of gum arabic, neither brilliant nor transparent. The finest, however, are colorless, and appear like rock-crystals.
In Brazil, where great numbers of diamonds, chiefly of small size, have been discovered, the method of searching for them is to wash the sand of certain rivers in a manner precisely similar to that employed in the gold fields, namely, by prospecting pans. A shovelful of earth is thrown into the pan, which is then immersed in water, and gently moved about. As the washing goes on, the pebbles, dirt and sand are removed, and the pan then contains about a pint of thin mud. Great caution is now observed, and ultimately there remains only a small quantity of sand. The diamonds and particles of gold, if present, sink to the bottom, being heavier, and are selected and removed by the practiced fingers of the operator. But how shall the gems be detected by one who has had no experience, and who in a jeweler’s shop could not separate them from quartz or French paste? The difficulty can only be overcome by testing such stones as may be suspected to be precious. Let these be tried by the very sure operation of attempting to cut with their sharp corners glass, crystal or quartz. When too minute to be held between the finger and thumb, the specimens may be pressed into the end of a stick of hard wood and run along the surface of window glass. A diamond will make its mark, and cause, too, a ready fracture in the line over which it has traveled. It will also easily scratch rock-crystal, as no other crystal will.
But a more certain and peculiar characteristic of the diamond lies in the form of its crystals. The ruby and topaz will scratch quartz, but no mineral which will scratch quartz has the curved edges of the diamond. In small crystals this peculiarity can be seen only by means of a magnifying glass; but it is invariably present. Interrupted, convex or rounded angles, are sure indications of genuineness. Quartz crystal is surrounded by six faces; the diamond by four. The diamond breaks with difficulty; and hence a test sometimes used is to place the specimen between two hard bodies, as a couple of coins, and force them together with the hands. Such a pressure will crush a particle of quartz, but the diamond will only indent the metal.
The value of the diamond is estimated by the carat, which is equal to about four grains, and the value increases rapidly with its weight. If a small, rough diamond weigh four grains, its value is about $10; if eight grains, $40; if sixteen grains, $640. A cut diamond of one carat is worth from $50 to $100.
The imperfections of the diamond, and, in fact, of all cut gems, are made visible by putting them into oil of cassia, when the slightest flaw will be seen.
A diamond weighing ten carats is “princely;” but not one in ten thousand weighs so much.
If a rough diamond resemble a drop of clear spring water, in the middle of which you perceive a strong light; or if it has a rough coat, so that you can hardly see through it, but white, and as if made rough by art, yet clear of flaws or veins; or, if the coat be smooth and bright, with a tincture of green in it,—it is a good stone. If it has a milky cast, or a yellowish-green coat, beware of it. Rough diamonds with a greenish crust are the most limpid when cut.
Diamonds are found in loose pebbly earth, along with gold, a little way below the surface, towards the lower outlet of broad valleys, rather than upon the ridges of the adjoining hills.
Searching for Gold.—The paying localities of gold deposits are the slopes of the Rocky and Alleghany Mountains. Gold need not be looked for in the anthracite and bituminous coal-fields nor in limestone rock. It is seldom found in the beds of rivers. The thing itself is the surest indication of its existence. If soil or sand is “washed” as described in Chapter V., and the particles of gold are not heavy enough to remain at the bottom but float away, the bed will not pay.
Along streams rather high up among the mountains, and in the gravelly drift covering the slopes of the valley below, are the best prospects. Where the stream meets an obstacle in its path or makes a bend or has deep holes, there we may look for “pockets” of gold. Black or red sands are usually richest. Gold-bearing rock is a slate or granite abounding in rusty looking quartz veins, the latter containing iron pyrites or cavities. Almost all iron pyrites and silver ores, may be worked for gold. When the quartz veins are thin and numerous rather than massive, and lie near the surface, they are considered most profitable. Few veins can be worked with profit very far down. As traces of gold may be found almost everywhere, no one should indulge in speculation before calculating the percentage and the cost of extraction. Gold-hunting, after all, is a lottery with more blanks than prizes.
The substances most frequently mistaken for gold are iron pyrites, copper pyrites and mica. The precious metal is easily distinguished from these by its malleability (flattening under the hammer) and its great weight, sinking rapidly in water.
Searching for Silver.—This metal is usually found with lead ore and native copper. Slates and sandstones intersected by igneous rocks as trap and porphyry, are good localities. Pure silver is often found in or near iron ores and the dark brown zinc blende. The Colorado silver lodes are porous at the surface and colored more or less red or green. Any rock suspected of containing silver should be powdered and dissolved in nitric acid. Pour off the liquid and add to it a solution of salt. If a white powder falls to the bottom which upon exposure turns black, there is silver in it. Silver mines increase in value as in depth, whereas gold diminishes as we descend.
Searching for Copper.—The copper ores, after exposure, or after being dipped in vinegar, are almost invariably green on the surface. They are most abundant near trap dykes. The pyrites is generally found in lead mines, and in granite and clay-slate. Copper very rarely occurs in the new formations, as along the Atlantic and Gulf borders, and in the Mississippi Valley south of Cairo.
Searching for Lead.—Lead is seldom discovered in the surface soil. It is also in vain to look for it in the coal region and along the coast. It must be sought in steep hills, in limestone and slate rocks. A surface cut by frequent ravines or covered by vegetation in lines, indicates mineral crevices. The galena from the slate is said to contain more silver than that from the limestone. The purest specimens of galena are poorest in silver; the small veins are richest in the more precious metal. A lead vein is thickest in limestone, thinner in sandstone and thinnest in slate.
Searching for Iron.—Any heavy mineral of a black, brown, red or yellow color may be suspected to be iron. To prove it, dissolve some in oil of vitriol and pour in an infusion of nut-gall or oak-bark; if it turns black, iron is present. If a ton of rich magnetic ore costs more than $4 at the furnace, good hematite more than $3, and poor ores more than $1.50 or $2, they are too expensive to pay, unless iron is unusually high. Deep mining for iron is not profitable. Generally speaking, a bed of good iron ore, a foot thick, will repay the cost of stripping it of soil, etc., twelve feet thick. Red and yellow earths, called ochres, contain iron. Magnetic ore is easily found by a compass.
CHAPTER V.
ASSAY OF ORES.
WHEN AN ORE WILL PAY—WASHING FOR GOLD AND PLATINUM—HOW TO ASSAY GOLD IN THE SIMPLEST WAY—TO TEST ANY ROCK FOR GOLD AND SILVER—TO FIND THE PURITY OF GOLD—TO DETECT AND ASSAY SILVER ORES—ASSAY OF COPPER, IRON, ZINC, TIN AND LEAD ORES—READY METHOD OF TESTING GRAPHITE.
ONE of the first questions asked after the discovery of a metallic ore, is—“will it pay?” We propose to state in plain words a method of determining the character and value of the principal ores, so that any intelligent man, however unscientific, may answer his own question. The chemical analysis or exact assaying of ores is too complicated, and must be left to professional assayers.
“Will it pay?” is an important query; for many ores of even precious metals, are not “paying.” Whether an ore is profitable depends not so much upon the relative value of the metal as upon the ease of separating it from the rock or “gangue” as it is called. Thus the minimum percentage of metal, below which the working of the ore ceases to be profitable is—
| Of | Iron, | 25 | per cent. |
| Zinc, | 20 | “ | |
| Lead, | 20 | “ | |
| Antimony, | 20 | “ | |
| Copper, | 02 | “ | |
| Tin, | 01½ | “ | |
| Quicksilver, | 01 | “ | |
| Silver, | 1/2000 | “ | |
| Platinum, | 1/10000 | “ | |
| Gold, | 1/100000 | “ |
That is, an ore of iron which contains less than 25 per cent. of metal will not pay for working; for the reduction of iron in comparison with copper ore is very difficult. Gold is very easily extracted, and hence some quartz rocks which do not apparently contain a particle of gold, pay well, a bushel of rock often yielding half an ounce.
Iron occurs in large masses or beds; but the other metals are scattered in fragments through sand or soil, or exist in veins running through rocks.
Washing for Gold and Platinum.—This operation, called “panning,” is the oldest and simplest method of extracting the precious metals. At the present time, it furnishes to Russia nearly all the gold produced in that empire. It is based on the principle that substances of different weights may be separated by means of water,—the heaviest going to the bottom first. To examine the bank or bed of a river, suspected to contain gold, fill a milk-pan with the sands and carry it to a tub or pool of quiet water. Dip it under, stirring the mass with one hand or a stick. Then pour off the muddy water, fill with fresh water stirring again, and again pour off the light sand, clay, etc. Scales of gold will sink fast; mica flakes will take their time. Repeat this process till all the fine particles are washed off; then allow just enough water to enter the pan as will cover the sand. By shaking the pan and gradually lowering the side by which it is held, the light sand will flow off, leaving in the corner a heap of coarse sand. Put in a small quantity of water and turn the pan around so as to create a gentle current, when the precious metal, if there be any, can be easily detected,—the gold by its bright lustre, the platinum by its lead color, and both by their malleability. Particles of gold are of uniform color and are either flat or rounded; while other yellow grains are angular. Holding the pan in the sunshine, secure any glittering glassy crystals, and test them for diamonds or rock-crystals. A magnet will remove any particles of magnetic iron-ore.
Assay of Gold Ore.—Gold may be found in quartz rock, in iron and copper pyrites, and in silver ores.
To ascertain if any gold is present in quartz, reduce the rock to powder and sift it. A certain quantity, say half a peck, is then washed as above described, till a manageable quantity of sand is left. If there is any show of gold, dry the mass and put it in a bowl or glass dish, and add an ounce of quicksilver, stirring the mixture well with a wooden rod. The quicksilver, which will unite with every particle of gold which may be there, is then poured off into a soft leather (chamois) bag. This is squeezed to remove superfluous quicksilver, and a pasty amalgam is left, which is put into an iron vessel and heated red hot. The yellow powder remaining is mixed with saltpetre and melted, when a button of pure gold will be found in the crucible. Quartz ores should yield $6 to the ton in order to pay.
To test pyrites for gold, reduce a given quantity to powder and wash as before; then roast the residue at a red heat. Upon cooling, add quicksilver and treat as just described. Pyrites should yield $1 of gold to the bushel of ore to be profitable.
Native silver often contains gold. To separate them, carefully flatten the alloy with a smooth hammer on an anvil, and then boil it in strong nitric acid in a glass flask for about ten minutes. Carefully pour off the acid into a vial, and wash the powder in the flask (which is fine gold) with water and dry. To the liquid in the vial add a solution of common salt. The white powder which falls should be removed, washed with water, and fused with powdered chalk or iron filings; a button of pure silver is the result.
Any substance supposed to be or to contain gold may be tested by dissolving it powdered in aqua regia and then pouring in a solution of copperas; if there is gold, the reddish-brown precipitate, by rubbing, assumes a bright metallic lustre.
To tell whether a globule of silver has any gold in it, put it on a white porcelain dish and moisten it with a drop of nitric acid: if it is pure silver, it will dissolve and retain its white color; if mixed with gold, it will soon turn gray or black.
To test the purity of gold, rub some of it off on a hard black flint slate, and apply to the mark a drop of aqua fortis. If the gold is pure, the yellow streak remains unchanged, but if alloyed it partly disappears; if it is only an imitation of gold, it vanishes altogether.
A ready method of finding the amount of gold in a quartz rock with considerable accuracy, is by taking the specific gravity of the rock (well cleaned) as given on page 13. If the gravity is not over 2.7, it contains little or no gold. If it is 3, it very likely is gold-bearing, although pyrites may be present. But if it is over 5, it is undoubtedly auriferous, and if 12, it is very rich in gold.
It is generally considered that the sand of any river is worth working for the gold it contains, provided it will yield twenty-four grains to the hundred weight.
Assay of Silver Ore.—Pure silver is easily recognized. But lead and copper ores often contain a large percentage of the precious metal.
To detect silver in lead ore, dissolve the powdered ore in strong nitric acid; pour off the liquid and insert a piece of pure copper. If silver is present, it will go to the bottom. Or, add to the liquid a solution of common salt, and it will instantly become cloudy or white. If lead ore yields three ounces of silver to a ton, it may be worked for the silver as well as the lead. In Colorado, the average value of silver-bearing galena is $100 per ton.
To test the copper ores for silver, dissolve them in nitric acid; then add a few drops of muriatic acid, and if silver is present, a white curdy precipitate will fall to the bottom. Native copper, when polished, often shows white spots of silver.
To estimate the proportion of silver in lead ore, reduce a known quantity of the clear ore to powder, mix with a little dry soda and a few nails, and heat in a round-bottomed iron pot or crucible. The lead which is obtained should then be put in a cup having ashes at the bottom, and strongly heated in an open furnace. A globule of silver will be left, if any is present, and being weighed, the percentage can be found.
Rich silver ores may be reduced by mixing them with ten parts of common salt, and exposing the mass for hours in an open furnace, stirring it frequently. When cold reduce to powder and mix with an equal quantity of quicksilver and enough water to make a paste, and agitate the mixture for two days, when the amalgam will fall to the bottom. The amalgam is then squeezed in a leather bag and washed.
Silver glance will yield its metal by heating it before a blow-pipe.
Assay of Copper Ore.—When the ore is native copper and rock, as at Lake Superior, it should be pounded and the earthy matter washed away. Then mix with a little potash or soda and bring to a high heat in a crucible.
Other copper ores may be tested by dissolving them powdered in dilute aqua regia. The presence of silver will be shown by a white powder on the bottom. Then add considerable ammonia. If there is any copper a blue liquor will be produced. Strain this through tissue paper, and evaporate to dryness. Dissolve the residue in muriatic acid, and by putting in a piece of iron or zinc, the copper will fall down. Or, add to this solution pure potash; dry and weigh the powder thrown down; every 5 parts of it contains 4 parts of copper.
Gray copper and red copper ores may be assayed by heating with charcoal, (both powdered,) in a furnace. Malachite and azurite should be smelted with borax; Copper pyrites and silicate of copper with soda or powdered marble.
A ton of copper ore which contains ten per cent. of metal, pays $25 at the furnace. The ore of copper when roasted, turns black; and when thrown into nitric acid makes a sky-blue solution. A clean knife-blade put into this solution will be coated with copper.
Assay of Iron Ore.—Take a known quantity of the ore in fine powder and mix thoroughly with dry borax (or with one part of fluor spar, one of charcoal and four of salt,) and expose it for an hour in a covered crucible lined with charcoal to a white heat in a wind-furnace for an hour. A button of iron will be found at the bottom, which determines the percentage.
Assay of Zinc Ore.—If the weighed ore is roasted with powdered charcoal, white flowers of zinc will be formed on a piece of cold iron held over it. After thorough roasting, the residue should be weighed; the loss is the oxide of zinc, and every 100 parts of this contain 81 of metal.
All the ores of zinc will dissolve in either nitric or hot sulphuric acid.
Assay of Tin Ore.—Tin-stone will yield up its metal if mixed with charcoal, borax and soda, and heated on the hearth of a furnace or before a blow-pipe.
The presence of tin may be tested by dissolving the metal thus roasted out, in aqua regia and adding a decoction of Brazil-wood: if the metal was tin, the liquid will be colored a beautiful crimson.
Assay of Lead Ore.—Both galena and cerussite are rich ores, and when abundant pay well. They are easily reduced by heat, the former being usually mixed with charcoal and iron filings. If a western backwoodsman wants shot or bullets, he kindles a fire in a hollow tree or an old stump, puts some galena on the charred wood, and melts it down. After cooling, he finds the metal at the bottom. The smelting of a ton of lead costs about $6. The average price per ton of galena is $30. When galena is dissolved in warm nitric acid, a clean plate of zinc placed in it will be coated with brilliant blades of lead; if the galena contains silver, a plate of copper will be served in the same way. A solution of chromate of potash poured into a solution of lead ore in nitric acid will throw down a yellow powder.
To Test the Purity of Graphite.—Its value depends upon the amount of its carbon. Pulverize and then dry at a heat of about 350 degrees, twenty grains of it; then place it in a tube of hard glass four or five inches long, half an inch wide and closed at one end. Add twenty times as much well dried oxide of lead and well mix. Weigh the tube and contents, and afterwards heat before a blow-pipe till the contents are completely fused and no longer evolve gases. Ten minutes will suffice for this. Allow the tube to cool and weigh it. The loss in weight is carbonic acid. For every twenty-eight parts of loss there must have been twelve of carbon.
CHAPTER VI.
MINERAL SPRINGS.
WHAT ARE MINERAL SPRINGS—GENERAL LOCATION—GAS SPRINGS—IRON SPRINGS—SULPHUR SPRINGS—ALUM SPRINGS—EPSOM SPRINGS—SALT SPRINGS—WARM SPRINGS—ARTESIAN WELLS AND OIL WELLS, AND WHERE TO BORE FOR THEM.
ANY spring which contains a large amount of foreign matter, as gas, salts and earthy ingredients, is called mineral water. The special prominence of any ingredient gives it its particular name. Many iron springs contain salt, salt springs contain iron, and both may contain gas; the name is derived from the most prominent ingredient.
Our country is rich in mineral springs; there is not a State without one. But in general they are most numerous in hilly or mountainous regions, especially where the rocks are much deranged in position, or “faulted,” as the miners say. As for example, in Eastern New York and in the valley between the Blue Ridge and the Alleghany from Harper’s Ferry to the Natural Bridge. The Pacific States, also, are as remarkable for the number and variety of their mineral springs as for their metallic ores.
Carbonated or Gas Springs.—Springs of this class have a peculiar sparkling character and are continually sending up bubbles of gas. When the quantity of gas is small, it may be detected by adding a little lime water which will give it a milky appearance and deposit a white sediment; or, dip in a piece of blue litmus paper (which can be had of most druggists), and if there is any carbonic acid gas in the water, it will be reddened; or, pour in a little vinegar, stir well, and then add a little finely powdered sugar, when the gas, if it is there, will rise in small bubbles.
The most celebrated carbonated springs are the following: Saratoga and Ballston, N. Y.; Clarendon, Vt.; Sweet Springs in Shover’s Valley, Pa.; Bladon and Bailey Springs, Ala.; “Boiling Springs” near Pike’s Peak, Col.; Beer Springs near Bear River, Or. These springs contain salt, soda, magnesia, lime and iron, and are sometimes classed as saline, soda or chalybeate springs.
Chalybeate or Iron Springs.—The presence of iron in a spring may be ascertained by pouring into it an infusion of nut-galls, of logwood or of tan-bark, which will change it immediately to a black or dark color. If the water contains much iron, it may be recognized by its inky taste and by a yellowish powder on the border of the spring or at the bottom of a tumbler when allowed to stand awhile.
If waters have a cool but earthy taste, they contain lime; if bitter, they have magnesia. The “soda springs,” so called, are often only saline, carbonated or magnesia waters.
The most famous iron springs are at Saratoga, Sandlake and Catskill, N. Y.; West Bethel, Fryeburg, Eberne and Bethel, Me.; Schooley’s Mountain in Washington, N. J.; Bedford, Pittsburg, Frankfort and York, Pa.; Brandywine Springs, Del.; Red Sweet Springs in Monroe County, Rawley’s Spring in Rockingham County, and Huguenot Springs in Powhattan County, Va.; in Bath County, Ky.; Yellow Springs, O.; twenty miles east of Knoxville, Tenn.; Madison County, Geo.; Raymond and Lynchburg, Miss.; near Ogden City, Utah; near Mt. Shasta, Col.
Sulphur Springs.—These are easily recognized by their unpleasant odor, resembling that of rotten eggs. The water blackens silver and a solution of sugar of lead.
Sulphur springs are very numerous. The best known are at Saratoga, Sharon, Clifton, Avon, Manlius, Chittenango, Dryden and Richfield, N. Y.; Highgate and Newburg, Vt.; Togus, Bethel and West Newfield, Me.; Shover’s Valley, Carlisle and Doubling Gap, Pa.; Winchester and Warrenton, Va.; Greenbrier and Monroe Counties, W. Va.; Bath County, Ky.; White’s Creek near Nashville and in Granger County, Tenn.; Spartanburg, S. C.; Butts County, Geo.; Tallahatta, Ala.; Tampa, Fla.; near Bitter Creek and Great Salt Lake, Utah; along the Yellowstone River, Mont.; Jackson, Cal.
Acid or Alum Springs.—These waters have a more or less sour taste and redden blue litmus-paper.
They are found at Byron and Oak Orchard, N. Y.; Blossburg, Pa.; Bath, Richmond and Rockbridge, Va.
Magnesian or Epsom Springs.—These have a bitter taste. To test any water for magnesia, add to a glass of it a solution of phosphate of soda and some hartshorn; if magnesia is present, the liquid first becomes turbid, and finally minute crystals fall to the bottom.
There are Epsom springs at Harrodsburg and Perryville, Ky.; Westport, O.; Raymond, Miss.; Orange County, Ind.; Scott County, W. Va.
Saline or Salt Springs.—These contain a large percentage of common salt, and are recognized by their taste. They generally contain many ingredients, (generally seven or eight,) but the salt predominates. A well should contain at least ten per cent. of salt to pay for working. The Syracuse spring yields a bushel of salt to every thirty-three gallons; while the Great Salt Lake contains 22 per cent. Among the most important salt wells are those at Syracuse, Salina and Liverpool, N. Y.; Lubec, Me.; Shannondale, Va.; Bath County, Ky.; Athens County, O.; Hartford, Ind.; Saginaw, Mich.; Oneida, Idaho.
Thermal or Warm Springs.—Any spring is so called, the temperature of which throughout the year is above that of the soil around it. They generally occur near the line of junction between the granite or igneous rocks and the stratified rock (slate or limestone) resting upon its flanks. The temperature of such waters in the United States ranges from 73 to 200 degrees, the latter being reached by the Geysers of Montana. Many iron and sulphur springs are also thermal.
The most noted warm springs are at Lebanon, N. Y.; in Bath, Berkley, Monroe and Scott Counties, Va.; Buncombe Counties, N. C.; French Brood River, Tenn.; Meriwether County, Geo.; Washitaw, Ark.; Salt Lake Valley, Utah; near Pyramid Lake, Nev.; along the Malheur and Fall Rivers, Or.; Lincoln Valley, Idaho; on Gardiner’s River, in Madison County, and especially in the Yellowstone Basin, Mont.
Artesian Wells.—To sink a flowing well with any reasonable prospect of success, it is essential that the spot selected should be lower than land in the vicinity, although those higher elevations may be several miles away. The layers of the rocks, also, should dip towards the spot rather than away from it. The best indication, but not a certain one, is a great basin-shaped valley, to the centre of which the rocks dip on one or more sides. Sandy, lime and slate rocks are more propitious than granite.
Oil Wells.—Where there are marks of disturbance and misplacement of the rocks, there the experienced sink wells. Rugged hills and sharply-defined valleys are, generally, signs of such dislocation. The line or “break” from which the rocks dip like the roof of a house is considered most favorable. There is no such thing as an “oil rock,” for the oil is found at different depths, and the fissure containing it is more or less vertical. In Pennsylvania, the greatest flowing wells have been found in the third sand rock. No limestone has afforded any large supply of oil. Coal in no large quantities is ever found upon or in the immediate vicinity of the oil territory. The “show of oil” increases in value as a sign, with the depth at which it is found. Especially is the finding of a large amount of imprisoned gas, though no oil may be present, regarded as a good indication that oil is near. In the bituminous coal region, a gas spring indicates the probable existence of oil in the rocks below. But generally, “surface shows” are seductive. The great oil belt runs south-westerly from Oil Creek, Pa., to Burning Springs, West Va. But Ohio, Kentucky, Tennessee, Georgia, Alabama, Missouri, Texas, Illinois, Indiana, Michigan and Southern California are also rich in petroleum.
CHAPTER VII.
ARTIFICIAL JEWELRY—HOW MADE AND HOW DETECTED.
MOCK DIAMONDS—“PARIS BRILLIANTS”—THE MANUFACTURE OF PASTES—FALSE RUBY, TOPAZ, SAPPHIRE, EMERALD AND CARNELIAN—HOW TO DISTINGUISH TRUE AND FALSE GEMS—IMITATION PEARL AND CORAL—ARTIFICIAL GOLD—LIST OF PRECIOUS STONES.
“BRISTOL Stones,” “Irish Diamonds,” “Cape May Diamonds,” and “California Diamonds,” are skillfully-cut quartz crystals. They are easily detected by the file and by their lightness.
“Paris Brilliants” are more dangerous counterfeits, and are very often sold for genuine. The great establishment of Boarguiguon, in Paris, is the most famous manufactory of artificial gems in the world, employing about one hundred hands. The gems are such perfect imitations that they can be distinguished from real stones only by the closest scrutiny of those experienced in such matters. They fail chiefly in hardness; in brilliancy and gravity they nearly or quite equal the genuine.
Nature has made the most precious stones with the most common materials. The diamond is purified charcoal; while the matter of clay and white pebbles is the base of all other gems.
The chemist has imitated nature in the production of colored gems. The base of these imitations, called “pastes,” is “strass”—a white glass compound of 300 parts of pure sand, 96 of potash, 27 of borax, 514 of white lead, and one of arsenic. The mixture is put into a crucible and kept at a high heat for 24 hours. This is the philosopher’s stone which competes with Golconda. The uncolored glass is used in making mock diamonds and white topaz. Another paste which has very great brilliancy, and, unfortunately, the same gravity as the diamond, is made by melting 100 parts of pure sand, 150 of red lead, 30 of calcined potash, 10 of calcined borax and one of arsenic, keeping the mixture melted for two or three days and then cooling very slowly. Each ingredient is separately reduced to a fine powder.
False Ruby is made by fusing together of strass one ounce and six drams, glass of antimony 37 grains, and purple of cassius one grain; then add eight parts more of strass and fuse for thirty hours; cool and remelt pieces in a blow-pipe. Or, melt five ounces of strass and one dram of manganese.
False Topaz can be made from 1008 grains of strass, 43 grains of glass of antimony and one grain of purple of cassius.
False Sapphire.—Add to eight ounces of strass 52 grains of pure oxide of cobalt.
False Emerald.—To one pound of strass add one dram of verdigris and fifteen grains of crocus martis. Or, take 2304 grains of strass, 21 grains of green oxide of copper, and one grain of oxide of chrome. Or, take an ounce and a half of rock-crystal, six drams of dry soda, two drams of dry borax, two drams of red lead, one dram of nitre, twenty grains of red oxide of iron, and ten grains of green carbonate of copper.
False Carnelian.—Strass two pounds, glass of antimony one pound, rouge two ounces, manganese one dram.
False Amethysts and Opals are manufactured; but the fine opal defies imitation, and the amethyst is too common in nature to allow much margin for the “pastes.”
In distinguishing true and false gems, no one character should be depended upon. All genuine stones will bear rough handling; if the merchant says “hands off,” refuse to purchase. Any gem worth buying is worth testing.
First: try the hardness. The file will make no impression on the diamond and ruby, and will with difficulty scratch the other gems; while the “pastes” are easily marred. All the precious stones scratch window glass, although opal will not attack common bottle glass. All imitations easily yield to sand. The sapphire is the hardest of colored gems, and opal is the softest. The emerald will hardly scratch rock-crystal; its counterfeit not at all. Topaz will scratch ordinary ruby, but will not touch sapphire.
Secondly: as to weight. This is the most accurate method, but the stone must be taken from its setting. The mode of taking the gravity has already been given (page 13), and the amount of each is stated in Chapter II. Garnet is the heaviest of gems; weighed in water it loses only one-fourth of its weight; i. e., if a red garnet be suspended by a fine thread from a delicate balance and immersed in a glass of water under it, one-quarter of its ordinary weight in air must be added to the pan from which it is suspended to restore the equilibrium. In like manner, ruby and sapphire lose a little more. The diamond and white topaz lose two-sevenths of their weight. Rock-crystal, amethyst, carnelian and agate lose five-thirteenths; and opal about one-half, being the lightest of gems. The emerald loses more than one-third.
As “paste” can be made so as to have the same specific gravity as the genuine article, this test alone can not be relied upon; but very few of the imitations are so carefully made. The test is very convenient in distinguishing gems of like color from each other, as oriental ruby, spinel ruby and red tourmaline, and green tourmaline and emerald.
Thirdly: characteristics depending on light and electricity. It is not easy to look through a diamond of the first water, while imitations readily permit objects to be seen through them. A very delicate and perfect test of a diamond, distinguishing it from all colorless gems, as white topaz, white sapphire and white zircon, but not from “pastes,” is to look through it at a pin-hole in a card. This requires some dexterity, and the gem should be fixed to a steady object by a bit of wax at a proper distance. A true diamond will show but one hole, all the others will show two. As white topaz, when large, is a magnificent stone, it is often palmed off for a diamond of great value; but this test is invariably certain.
A true diamond retains its brilliancy under water.
When a colored stone is placed in the path of the solar spectrum (the row of seven colors into which sunlight is separated by a prism), its color will vary with the portion of the spectrum which falls upon it; and two stones of the same color, but of a different nature, will exhibit different effects. Thus, a paste placed beside a fine colored gem, betrays its worthlessness. A simpler method of testing stones is to look at them through a bit of glass, colored red, yellow, blue or green. Every stone will exhibit, under this test, properties peculiar to itself, and by which its
nature may be recognized. This is also a severe test for the purity of tint; for if pure and unmixed, the stone will appear completely black in every other light but its own color. Milky and turbid stones can not bear this test.
A first-class ruby has the color of the blood as it spirts from an artery. The deeper the hue of the emerald the more it is valued; it loses none of its brilliancy by artificial light. The pale rose topaz, the kind most esteemed, is artificially colored by heating it.
If topaz or tourmaline be gently heated, it becomes electric and will attract a thread or suspended pith-ball. No imitation will do this. All real gems when rubbed will attract the pith-ball, and retain the power a long time; the pastes also become electric, but soon lose their attraction. Rub a glass tube with a piece of flannel and bring it near a suspended pith-ball; the latter will be strongly attracted and then repelled. Immediately rub a genuine diamond and bring it near the ball, and it will be attracted. A paste diamond thus rubbed would repel it.
Finally: the breath remains much longer on the pastes than on real gems. The former also betray under a magnifying glass small air bubbles. Diamonds and other first-class stones are always cold to the touch.
False Pearls.—These are glass beads coated with a mixture of three ounces of scales of the blay or bleak fish, half an ounce of fine glue, one ounce of white wax and one ounce of pulverized alabaster. Powdered opal is sometimes used; also the powdered pearl of the oyster and other shells soaked in vinegar, and made up with gum tragacanth. Artificial pearls are usually brittle, and do not weigh more than two-thirds as much as the genuine.
False Corals.—These are made of resin and vermilion; or of marble powder made into a paste with varnish or soluble glass and a little isinglass, colored by Chinese vermilion, and then moulded. They are used for setting in cheap jewelry. The knife shows it to be too soft to be genuine.
Artificial Gold.—The following oroid or imitation gold is sometimes sold for the genuine article which it closely resembles. Pure copper, 100 parts by weight, is melted in a crucible, and then 6 parts of magnesia, 3.6 of sal-ammoniac, 1.8 of quicklime and 9. of tartar are added separately and gradually in the form of powder. The whole is then stirred for about half an hour, and 17 parts of zinc or tin in small grains are thrown in and thoroughly mixed. The crucible is now covered and the mixture kept melted for half an hour longer, when it is skimmed and poured out.
Any imitation of gold may be detected by its weight, which is not one-half of what it should be, and by its dissolving in nitric acid while pure gold is untouched.
PRECIOUS STONES.
ARRANGED ACCORDING TO COLOR AND IN ORDER OF HARDNESS.
|
Limpid. Diamond, Sapphire, Topaz, Rock-Crystal. |
Yellow. Diamond, Topaz, Fire-Opal. |
Blue. Sapphire, Topaz, Spinel, Aquamarine, Indicolite, Turquoise, Kyanite. |
Red. Sapphire-Ruby, Spinel-Ruby, Brazilian-Topaz, Hyacinth, Carnelian, Rubellite, Garnet. |
| Green. Oriental Emerald, Chrysoberyl, Emerald, Chrysoprase, Chrysolite, Amazon Stone, Malachite. |
Violet. Oriental Amethyst, Amethyst. Black and Brown. Diamond, Tourmaline, Hyacinth, Garnet. |
CHAPTER VIII.
DISCOVERY OF GOLD IN CALIFORNIA.[4]
IT was on the 19th day of January, 1848, that James W. Marshall, while engaged in digging a race for a saw-mill at Coloma, about thirty-five miles eastward from Sutter’s Fort, found some pieces of yellow metal, which he and the half-dozen men working with him at the mill supposed to be gold. He felt confident that he had made a discovery of great importance, but he knew nothing of either chemistry or gold-mining, so he could not prove the nature of the metal nor tell how to obtain it in paying quantities. Every morning he went down to the race to look for the bits of the metal; but the other men at the mill thought Marshall was very wild in his ideas, and they continued their labors in building the mill, and in sowing wheat and planting vegetables. The swift current of the mill-race washed away a considerable body of earthy matter, leaving the coarse particles of gold behind; so Marshall’s collection of specimens continued to accumulate, and his associates began to think there might be something in his gold mines after all. About the middle of February, a Mr. Bennet, one of the party employed at the mill, went to San Francisco for the purpose of learning whether this metal was precious, and there he was introduced to Isaac Humphrey, who had washed for gold in Georgia. The experienced miner saw at a glance that he had the true stuff before him, and, after a few inquiries, he was satisfied that the diggings must be rich. He made immediate preparation to go to the mill, and tried
to persuade some of his friends to go with him; but they thought it would be only a waste of time and money, so he went with Bennet for his sole companion.
He arrived at Coloma on the 7th of March, and found the work at the mill going on as if no gold existed in the neighborhood. The next day he took a pan and spade, and washed some of the dirt in the bottom of the mill-race in places where Marshall had found his specimens, and, in a few hours, Humphrey declared that these mines were far richer than any in Georgia. He now made a rocker and went to work washing gold industriously, and every day yielded to him an ounce or two of metal. The men at the mill made rockers for themselves, and all were soon busy in search of the yellow metal. Everything else was abandoned; the rumor of the discovery spread slowly. In the middle of March Pearson B. Reading, the owner of a large ranch at the head of the Sacramento valley, happened to visit Sutter’s Fort, and hearing of the mining at Coloma, he went thither to see it. He said that if similarity of formation could be taken as a proof, there must be gold-mines near his ranch; so, after observing the method of washing, he posted off, and in a few weeks he was at work on the bars of Clear Creek, nearly two hundred miles north-westward from Coloma. A few days after Reading had left, John Bidwell, now representative of the northern district of the State in the lower House of Congress, came to Coloma, and the result of his visit was that, in less than a month, he had a party of Indians from his ranch washing gold on the bars of Feather River, twenty-five miles north-westward from Coloma. Thus the mines were opened at far distant points.
The first printed notice of the discovery of gold, was given in the California newspaper published in San Francisco on the 15th of March. On the 29th of May the same paper, announcing that its publication would be suspended, says:—“The whole country, from San Francisco to Los Angelos, and from the sea-shore to the base of the Sierra Nevada, resound with the sordid cry of gold! gold! gold! while the field is left half planted, the house half built, and everything neglected but the manufacture of picks and shovels, and the means of transportation to the spot where one man obtained one hundred and twenty-eight dollars’ worth of the real stuff in one day’s washing; and the average for all concerned, is twenty dollars per diem.”
The first to commence quartz mining in California were Capt. Wm. Jackson and Mr. Eliason, both Virginians, and the first machine used was a Chilian mill.
The Reid Mine, in North Carolina, was the first gold mine discovered and worked in the United States, and the only one in North America from which, up to 1825, gold was sent to the Mint.
CHAPTER IX.
DISCOVERY OF SILVER IN NEVADA, AND UNITED STATES GOLD AND SILVER STATISTICS.
SEPARATED from California by the snowy chain of the Sierra, the State of Nevada has been celebrated, since 1860, for its silver mining. In November, 1859, the news of the discovery of silver mines near Lake Washoe was confirmed at San Francisco; and in June, 1860, the mines of Washoe, the central western portion of the State, had already sent such rich results to Europe, that the French Ministers of Finance and Commerce despatched a mining engineer to Nevada to make a close inspection of these wonderful mines. It seemed as if the world were about to be inundated with silver, as it had been by gold ten years previously; and what would those economists now say, who had only recently counselled that the value of gold coin should be lowered or that gold should be demonetized on account of the disturbed relation of these precious metals—the bases of the standard of payment throughout the world generally. Whilst the French engineer visited Nevada and prepared his report, the miners of Washoe continued working their veins of metal. At the present time, 1881, the mines on the eastern slope of the Sierra Nevada annually produce about $12,500,000 of silver, chiefly from the Comstock lode; the total yield of gold from the quartz mines of California is about $17,000,000 per annum. The Comstock lode, in the State of Nevada, may be ranked among the most productive metalliferous deposits ever encountered in the history of mining enterprise; its productive capacity, as now being developed, surpassing, if the mass of its ores do not in richness equal, those of the most famous mines of Mexico and Peru.
The known limits of this lode cover a space of 22,546 feet in a nearly due north and south direction (magnetic). The variation of the needle in that locality is 16½ degrees east. Upon this extensive seat of metalliferous deposits, the mines are divided into three groups: the Virginia Group, seventeen mines, with claims of 13,549⅓ feet; Gold Hill Group, nine mines, of 6,397¼ feet; American Flat Group, three mines, of 2,600 feet. The three groups of twenty-nine mines thus occupy a total length on the lode of 22,546 feet. The Comstock lode was discovered in 1859, by a pit sunk for a water hole on the ground of the Ophir mine; milling the ore began in October of the same year, but the amount of bullion taken out in 1860 is estimated at but $100,000. Since then the Comstock has become the greatest gold and silver mine in the world. To the end of 1878 the yield was estimated at $291,162,205, as follows: From 1860 to 1870 inclusive, of gold and silver together, unclassified, $102,466,240; 1871 to 1878 inclusive, gold, $88,691,498, silver, $91,278,623; 1877 and 1878, gold and silver, unclassified, $1,725,844. Making allowance for the loss by slimes and tailings, the gross contents of the lode as worked up to 1878 are estimated at $363,961,205. About 6,500,000 tons of ore have been extracted in this time, which a good authority estimates of an average value to the company of $45 per ton of 2,000 pounds.[5]
ANNUAL PRODUCTION of GOLD and SILVER in the UNITED STATES from 1853 to 1880, inclusive.
[From the Reports of the Director of the Mint.]
The consumption of Gold and Silver in the Arts and Manufactures from 1874 to 1879, inclusive, in the United States, was estimated by the Director of the Mint, in 1879, as follows:
| YEAR. | Gold. | Silver. |
| 1874 | $4,578,328 | $4,406,560 |
| 1875 | 5,382,098 | 4,237,841 |
| 1876 | 4,153,184 | 3,812,018 |
| 1877 | 3,687,192 | 3,774,240 |
| 1878 | 5,078,701 | 5,210,152 |
| 1879 | 3,899,125 | 5,977,300 |
INDEX.
[A], [B], [C], [D], [E], [F], [G], [H], [I], [J], [K], [L], [M], [N], [O], [P], [Q], [R], [S], [T], [U], [V], [W], [Z]
Acid or alum springs, [109]
Agate, [20], [21]
localities, [21]
value, [20]
Alleghenies, [14]
Alum, [21]
localities, [21], [22]
springs, [109]
value, [21]
American Flat group, silver mines, [136]
Amethyst, [22]
false, how made, [117]
localities, [22]
value, [22]
Anthracite, [22], [23]
localities, [23]
value, [23]
Antimony ore, [23], [24]
localities, [23]
value, [23]
Artesian Wells, [111], [112]
Artificial gold, how made, [125]
jewelry, how made and detected, [114-125]
Asbestus, [24]
localities, [24]
value, [24]
Asphaltum, [24], [25]
localities, [25]
value, [25]
Assay of copper ore, [100-102]
gold ore, [95-98]
iron ore, [102]
lead ore, [103], [104]
ores, [92-104]
silver ore, [99], [100]
tin ore, [102], [103]
zinc ore, [102]
Atlantic coast, [14]
Azurite, [25]
localities, [25]
smelting, [101]
value, [25]
Baryta, localities, [26]
or heavy spar, [26]
value, [26]
Bidwell, John, [130-132]
Bituminous coal, [27]
localities, [27]
region, [14]
Blende, [27], [28]
localities, [28]
value, [28]
Blowpipe, [17]
Bog iron ore, [29]
localities, [29]
value, [29]
Boring, [83]
Brazil, diamonds in, [84]
Bristol stones, [114]
Brittle silver ore, [30]
localities, [30]
value, [30]
Brown coal, [30]
localities, [30]
value, [30]
Brown Hematite or Limonite, [56], [57]
Calamine, [31]
localities, [31]
value, [31]
California diamonds, [114]
discovery of gold in, [127-133]
Cannel coal, [31], [32]
localities, [32]
value, [32]
Cape May diamonds, [114]
Carbonated or gas spring, [106], [107]
Carnelian, [32]
false, how made, [117]
localities, [32]
value, [32]
Celestine, [32], [33]
localities, [33]
value, [33]
Cerussite, [33]
and Galena, reduction of, [103]
localities, [33]
value, [33]
Chalybeate or iron springs, [107], [108]
Chromic iron, [34]
localities, [34]
value, [34]
Cinabar, [34], [35]
localities, [35]
value, [35]
Clear Creek, Cal., gold in, [132]
Coal, anthracite, [22]
bituminous, [27]
brown, [30]
cannel, [31], [32]
Cobalt pyrites, [35]
localities, [33]
value, [35]
Coloma, Cal., discovery of gold there, [127]
Colorado silver lodes, [89]
Colors, distinction of minerals by, [12]
Comstock Lode, [135-137]
gold and silver produced from, [136], [137]
Connecticut river valley, [14]
Copper, [36]
glauce, [36]
localities, [36]
value, [36]
gray copper ore, assaying, [101]
localities, [36]
nickel, [37]
localities, [37]
value, [37]
ore, assay of, [100-102]
gray, [51]
red, [65]
red, assaying, [101]
variegated, [78]
ores, test for silver, [99]
testing, [100-102]
silver in, [101]
percentage of in ores, which will pay, [101]
pyrites, [37], [38], [90]
localities, [38]
smelting, [101]
value, [38]
searching for, [90]
seldom in new formations, [90]
silicate of, [70]
smelting, [101]
value, [36]
where found, [14], [90]
Corals, false, how made, [124]
Descriptive list of useful minerals, [20-80]
Diamond, [41]
estimation of the value of, [86]
imperfections of, [86]
localities, [41]
value, [41]
Diamonds, characteristics of, [85], [86]
colors of, [83]
finest, [84]
in Brazil, [84]
in their native state, [83]
mode of discovering in Brazil, [84]
prospecting for, [83-87]
where found, [87]
Directions for determining specimens by the key, [15-19]
Discovery of silver in Nevada, [134-137]
Effervescence in minerals, [12]
Eliason, Mr., [133]
Emerald, false, how made, [116]
to test, [118]
Emery, [41], [42]
localities, [42]
value, [42]
Epsom springs, [109], [110]
False amethyst, how made, [117]
carnelian, how made, [117]
corals, how made, [124]
False emerald, how made, [116]
opal, how made, [117]
pearls, how made, [124]
ruby, how made, [116]
sapphire, how made, [116]
topaz, how made, [116]
Feather river, Cal., gold in, [132]
Fluor spar, [42]
localities, [42]
value, [42]
Franklinite, [43]
localities, [43]
value, [43]
Galena, [43], [44]
and Cerussite, reduction of, [103]
localities, [44]
purest specimens poorest in silver, [91]
value, [43]
Garnet, [44], [45]
localities, [45]
the heaviest of gems, [118]
to test, [118]
value, [45]
Gas springs, [106], [107]
Gems, to test by weighing in water, [118]
true and false, how to distinguish, [117-124]
Glass, minerals which will not scratch, [16], [19]
minerals which will scratch, [15], [18]
Gold, [46-50]
and platinum, washing for, [94], [95]
and silver consumed in the arts in the United States, [137], [138]
and silver, production of the United States, [137], [138]
and silver where they abound, [14]
artificial, how made, [125]
bearing rock, [88]
bearing sands, [88]
extraction of, [93]
Hill group, silver mines, [136]
how distinguished, [89]
imitation, how to detect, [125]
in California, discovery of, [127-133]
in California, first announcement of discovery, [132]
in quartz rock, to find the amount of, [98]
localities, [46-50]
mine first worked in the United States, [133]
ore, assay of, [95-98]
searching for, [87-89]
substances mistaken for, [89]
testing any substance supposed to contain, [97]
to separate from silver, [97]
to test the purity of, [98]
where found, [87-89]
Granite regions, [14]
Graphite, [50], [51]
localities, [50], [51]
to test the purity of, [104]
value, [50]
Gravity, mode of determination of, [12]
Gray copper ore, [51]
localities, [51]
value, [51]
Gypsum, [14], [52]
localities, [52]
value, [52]
Heavy spar or baryta, [26]
Hematite, brown, [56], [57]
Horizontal beds, [82]
Horn silver, [53]
localities, [53]
value, [53]
Humphrey, Isaac, [128]
Indications for minerals, [81]
Irish Diamond, [114]
Iron, chromic, [34]
how it occurs, [94]
ore, [14]
assay of, [102]
bog, [29]
brown hematite, [56], [57]
lenticular, [56]
magnetic, [57], [58]
magnetic, found by the compass, [91]
micaceous, [62]
red hematite, [65], [66]
specular, [73], [74]
pyrites, [53], [54]
localities, [54]
value, [53], [54]
searching for, [91]
spathic, [73]
springs, [107], [108]
testing minerals for, [91]
Jackson, Captain Wm., [133]
Jasper, [54]
localities, [55]
value, [55]
Jewelry, artificial, how made and detected, [114-125]
Kaolin, [55], [56]
localities, [55]
value, [55]
Lead ore, assay of, [103], [104]
to detect silver in, [99]
searching for, [90]
veins, thickest, [91]
where found, [90]
Lenticular iron ore, [56]
localities, [56]
value, [56]
Limestone regions, [14]
Limonite or brown hematite, [56], [57]
localities, [57]
value, [57]
Magnesian springs, [109], [110]
Magnetic, [12]
iron ore, [57], [58]
found by the compass, [91]
localities, [58]
value, [58]
pyrites, [58], [59]
localities, [59]
value, [59]
Malachite, [59], [60], [101]
localities, [59], [60]
value, [59]
Manganese, oxyd of, [63], [64]
spar, [60]
localities, [60]
value, [60]
Marble, [60], [61]
localities, [61]
regions, [14]
Marshall, Jas. W., discovery of gold in California by, [127-131]
Metals, found near their source, [82]
how they occur, [94]
Mica, [61], [62]
localities, [62]
value, [62]
Micaceous iron ore, [62]
localities, [62]
value, [62]
Mineral riches, how discovered, [81]
springs, [105-112]
location of, [105]
no indications of ores, [83]
what are they, [105]
Minerals as a source of our nation’s wealth, [9]
descriptive list of, [20-80]
regions which offer best inducements to search for, [14]
sections of the United States, richest in, [14]
species in the United States, how many, [11]
specific gravity of, [12], [13]
useful in the United States, [11]
which will not scratch glass, [16], [19]
which will scratch glass [15], [18]
Mississippi Valley, [14]
Money in the rocks, [9]
Nickel, copper, [37]
Nitre, [63]
localities, [63]
value, [63]
Nodules, [82]
Ochres, [91]
Oil wells, [112], [113]
Opal, false, how made, [117]
the softest of colored gems, [118]
Opaque minerals, [12]
Ore on a hillside, indications of, [82]
veins generally vertical, [82]
when it will pay, [92]
Ores, assay of, [92-104]
minimum percentages of metal in which will pay, [93]
Oxyd of Manganese, [63], [64]
Pacific coast, [14]
Panning, [94], [95]
Paris brilliants, [114]
Pastes, composition of, [115]
Pearls, false, how made, [124]
Platinum, [64]
localities, [64]
value, [64]
washing for, [94], [95]
Pockets, [82]
Precious stones, color and order of hardness, [126]
Prospecting for diamonds, [83-87]
Pyrites, iron, [53], [54]
cobalt, [35]
copper, [37], [38], [90]
magnetic, [58], [59]
testing for gold, [96]
yield of gold by, [97]
Quartz mining in California, commencement of, [133]
ores, yield of, [96]
rock, to find the amount of gold in, [98]
testing for gold, [95], [96]
Quicksilver, use of in assaying, [96]
Reading, Pearson B., [131]
Read mine, first gold mine worked in United States, [133]
Red copper ore, [65]
localities, [65]
value, [65]
hematite, [65], [66]
localities, [66]
value, [65]
silver ore, [66]
localities, [66]
value, [66]
Rennselaerite, [67]
localities, [67]
value, [67]
River sand, worth working for gold, [98]
Rock crystal, [67]
localities, [67]
value, [67]
salt, [68]
localities, [68]
suspected of containing silver, treatment of, [89]
Rocky mountains, [14]
Ruby, characteristics of, [85]
false, how made, [116]
spinel, [74]
to test, [118], [123]
Russia, gold how obtained in, [94]
Rutile, [68]
localities, [68]
value, [68]
Saline or salt springs, [109], [110]
Salt springs, [110]
Sapphire, false, how made, [116]
the hardest of colored gems, [118]
to test, [118]
Searching for copper, [90]
diamonds, [83-87]
gold, [87-89]
iron, [91]
lead, [90]
silver, [89], [90]
Serpentine, [69]
localities, [69]
value, [69]
Shaft, cost of sinking, [83]
Silicate of copper, [70]
localities, [70]
smelting, [101]
value, [70]
Silver, [70], [71]
and gold, consumption in the arts in the United States, [137], [138]
and gold, production of the United States, [137], [138]
glance, [71]
localities, [71]
reducing, [100]
value, [71]
horn, [53]
in copper ores, [101]
in lead and copper ores, [99]
in lead ore, to detect, [99]
to estimate the proportion of, [99], [100]
in Nevada, [134-137]
localities, [70]
native gold in, [97]
ore, assay of, [99], [100]
brittle, [30]
red, [66]
ores, rich reduction of, [100]
pure easily recognized, [99]
searching for, [80], [90]
to test a globule of for gold, [97]
to test copper ores for, [99]
where found, [89]
Slate regions, [14]
Smaltine, [72]
localities, [72]
value, [72]
Smithsonite, [72]
localities, [72]
value, [72]
Spar manganese, [60]
Spathic iron, [73]
localities, [73]
value, [73]
Specific gravity, mode of determination of, [12], [13]
Specular iron ore, [73], [74]
localities, [74]
value, [74]
Spinel ruby, [74]
localities, [74]
value, [74]
Steatite, [75]
localities, [75]
value, [75]
Stones, precious, color and order of hardness, [126]
Strass for making false jewels, [115]
Strontianite, [75], [76]
localities, [76]
value, [76]
Sulphur, [76]
localities, [76]
springs, [108], [109]
Testing minerals, [15-19]
Thermal springs, [110], [111]
Tin ore, [76], [77]
assay of, [102], [103]
localities, [77]
value, [76]
presence of, testing for, [103]
Topaz, [77]
characteristics of, [85]
false, how made, [116]
localities, [77]
to test, [118], [120], [123]
value, [77]
Tourmaline, [77]
localities, [77]
to test, [123]
value, [77]
Translucent minerals, [12]
Trap regions, [14]
True and false gems, how to distinguish, [117-124]
United States, consumption of gold and silver in the arts, [137], [138]
gold and silver statistics of, [137], [138]
Useful minerals, descriptive list of, [20-80]
in the United States [11]
Valuable minerals disguised, [10]
Variegated copper ore, [78]
localities, [78]
value, [78]
Veins, lodes and beds most valuable, [82]
Virginia group, silver mines, [136]
Wad, [78], [79]
localities, [79]
value, [78]
Warm springs, [110], [111]
Washing for gold and platinum, [94], [95]
Washoe lake, silver mines near, [134]
Wells, artesian, [111], [112]
Willemite, [79]
localities, [79]
value, [79]
Zincite, [79], [80]
localities, [80]
value, [79]
Zinc ore, assay of, [102]
FOOTNOTES:
[1] The useful rocks, as granite, slate, sandstone, water-lime, etc., are not included. By “granite region” is meant one having rocks like New England, and therefore unlike Western New York or Illinois.
[2] That is, they are not so easily cut with a knife; they do not necessarily scratch marble.
[3] Only the best known localities in the United States are given. For these we are indebted mainly to Professor Dana’s great work on Mineralogy.
[4] From Simonin’s “Underground Life,” page 346.
[5] Church. The Comstock Lode, its Formation and History, N. Y., 1879, pp. 1-5.