The Anaconda mine in Butte is the largest producer of silver in the country. In 1896 its output was 5,000,000 ounces. The Anaconda is also the heaviest copper producer in the United States, its yield of copper being 125,350,693 pounds.
Sulphur. Brimstone is found native in the neighborhood of volcanoes, extinct or active. It is also derived from iron pyrites. Color, yellow. Hardness, 2. Specific gravity, 2. Luster, resinous. Smooth. Sectile. Texture, crystalline.
Talc. The scientific name of this mineral is steatite. It contains silica and magnesia. Its green color, pearly luster, and greasy feel, are very characteristic. It is not attacked by boiling sulphuric acid. Useful in the arts, but of no great value.
Tin. The composition of cassiterite, the commercial ore of tin, is SnO2; equal to 78.67 per cent. of metallic tin. Cassiterite or tin stone is a heavy ore which occurs in alluvial deposits or in the beds of streams. It will be one of the latest ores the young prospector will find himself able to name with certainty. Granite, with white mica as one of its constituents, has so far always been associated with tin. The American continent yields little tin, and it is not likely the prospector in either the western states or in Canada will stumble upon it, though a good deposit of stream tin would enrich him in a short time, for the metal is in great demand. The streak, when the metal is scratched with a knife point, is whitey-gray and very distinctive.
Tin may some day be found in the northern Rockies, as there is plenty of granite, which is favorable to this metal. It is worth about thirteen cents a pound, and a vein must yield more than five per cent. of metal to pay the cost of mining and dressing. Cassiterite, the principal tin ore, would have to be roasted. Most of the European tin mines were first worked for the copper they contained. The copper was found in the capping, but as they gained in depth they became more and more valuable for their tin. Some of the Cornish mines are three-quarters of a mile in depth. Very lately tin has been discovered and mined in vast quantities in the Straits Settlements, India. As it is found in the streams the expense of mining is very light, and it is killing the European mines. The Cornish miners put their tin ore on a shovel when they wish to test it. The sample is first crushed fine and a few skillful shakes get rid of all the gangue, leaving behind the tin and wolfram. This wolfram is always associated, in Cornwall, with the tin and it is got rid of by roasting. Australasia and Cornwall produce most of the tin used in commerce. Tin is not found native. Specific gravity of cassiterite is 6.5 to 7. Hardness, 6.5 to 7. Luster, vitreous to adamantine. Translucent to opaque. Brown, black, gray, red or yellow. Harsh. Brittle. Massive. The appearance of this metal is so variable that nothing but a test with reagents determines it with certainty. Granite is frequently the country rock in which tin is found.
Zinc. This is another ore that never occurs native. Calamine or silicate of zinc is the great producing ore. Composition: Zinc oxide, 67 per cent; silicate, 25 per cent; water, 8 per cent. Specific gravity, 3 to 3.7. Hardness, 4.6 to 5. Luster, vitreous. Translucent. White. Harsh. Brittle. Cleavage, perfect. Fracture, uneven. Texture, granular crystalline. Calamine is a difficult mineral to detect without experience, as when impure it does not look in the least like a metallic ore. It would be taken for clay or shale. This ore results from the decomposition of zinc blende. Blende contains 67 per cent. zinc and 33 per cent. sulphur. It is often dark brown or black from iron, otherwise it may be red, green or bluish. It is a troublesome impurity in silver ores. Smithsonite is a carbonate much resembling, and often found with, calamine. Other zinc ores are merely curiosities and do not affect the commercial value of the metal.
In the New Jersey mines the zinc ores are the oxides zincite and willemite, and the zinc-iron oxide franklinite. In the Missouri region, on the other hand, sphalerite and blende are the typical ores. Blende generally associates with the lead sulphide, galena. The Joplin district in southwestern Missouri and the adjoining region in Kansas are now mainly supplying the markets of the country, though the New Jersey deposits are very valuable.
Joplin ore assaying 58 to 62 per cent. has varied greatly in price during the past four years. The lowest quotation was $20 a ton, the highest $51.50.
Zinc is derived mainly from the following half dozen ores:
| Zinc. | |||
| Sphalerite | ZnS | 67.0 | per cent. |
| Zincite | ZnO | 80.3 | per cent. |
| Smithsonite | ZnOCO2 | 51.9 | per cent. |
| Franklinite | (Variable) (?) | 5.54 | per cent. |
| Willemite | 2ZnO.SO2 | 58.5 | per cent. |
| Calamine | 2ZnO.SiO2.HO2 | 54.2 | per cent. |