James Orton

“ 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{89} 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. ”

“ 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{98} 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. ”

“ 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{100} 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. ”

“ 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. ”

“ 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.{90} 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. ”

“ 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. ”

“ A trap-region, like the shore of Lake Superior and the Connecticut River Valley, is likely to be a good locality for copper and iron. The Mississippi Valley, or the region of Bituminous Coal, furnishes chiefly iron and lead; gold, silver and copper are seldom found. In general, where the layers of rock lie level and contain fossil shells, it is a locality good only for soft coal, (New York excepted) , iron ore, gypsum and salt. The regions of granite, slate, limestone, marble, etc., offer the greatest inducement to search for useful minerals.{15}
CHAPTER II. ”

“ The galena from the slate{91} 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 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{104} of copper will be served in the same way. ”

“ 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{94} 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. ”

“ 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{97} 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. ”

“ 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. ”

“ 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{116} 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. ”

“ No limestone has afforded any large supply of{113} 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. ”

“ 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 ”

“ 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{115} 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. ”

“ 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. ”

“ Localities.—Found in veins of quartz running through greenish or grayish slates, the quartz at the surface being generally full of cavities and rusted, and the slates below the surface often containing little cubic crystals of Iron Pyrites: also in the valleys traversed by mountain-streams and in the river sands and gravel below. Iron and Copper Pyrites, Galena and Blende frequently contain gold. Masses of quartz and pyrites from the gold-regions, which make no show of gold, sometimes pay well ”

“ 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. ”

“ Occurs in crystals and masses; brilliant lustre; brittle; easily broken; powder, when finely rubbed is black; can be cut with a knife; heated it gives off sulphur and melts; dissolves in nitric acid leaving a white powder at the bottom; gravity 7.5—or a little heavier than cast-iron.
Value.—The main source of lead (yielding eighty per cent) , and also smelted for the silver it contains. Used also in glazing stone-ware.{44}
Localities.—Generally found in limestone with Iron Pyrites, zinc-ore, etc. That found in slate is richest in silver. ”

“ 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. ”

“ 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{118} 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. ”

“ 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.{83}
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. ”

“ Exact color is not meant, but “red” stands for reddish, “yellow” for yellowish, “white” for a light gray up to the perfectly transparent. “Magnetic” means that the specimen disturbs the needle of a compass, or that a magnet will take up fine particles. A mineral is “opaque” if the light will not pass through either the edges or a thin fragment. A “translucent” mineral is either clear as crystal or only allows light to pass dimly through a thin portion. “Effervescence” is the bubbling produced by the escape of a gas, as in soda-water. ”

“ The object of this work is to point out those distinctions so clearly and in popular language that those who do not claim to be scientific may determine specimens for themselves; in other words, to furnish a key for the ready determination of all the useful minerals within the United States. [1]
Two hundred and forty-four mineral species have been found within the bounds of the Union. Of these only one-third are of any use to the practical man. ”

“ 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 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. ”

“ 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{125} 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. ”