Silver minerals

The mineral cerargyrite, horn-silver, AgCl, is interesting from a historical point of view. It was in crystals of this mineral that Carl Wilhelm Scheele first observed the blackening effect of light on silver halides. 

---

Lead and 2inc minerals are so intimately mixed in many deposits that they are mined together and then separated. Silver minerals are frequendy found in association with galena. 

Hg deposits are distributed along the MTL (Median-Tectonic Line) in Southwest Japan and in Northeast Hokkaido (Fig. 1.184). The deposits are vein or disseminated in form. The deposits are hosted by sedimentary and igneous rocks. No K-Ar age data on the deposits are available. However, from the age of host rocks, the age of igneous activities along MTL and the studies on the movement of MTL and K-Ar ages of Au-veins associated with Hg mineralization in Northeast Hokkaido (e.g., Khonomai), it is likely that these deposits formed at middle Miocene age. However, mercury mineralization in Kitami Province (north Hokkaido) occurred at approximately the same age as the epithermal gold-silver mineralization in the same district (4.5-5.3 Ma) (Maeda, 1997). 

Main opaque minerals include native gold, electrum, pyrite, pyrrhotite, chalcopy-rite, cubanite, sphalerite, arsenopyrite and tellurobismutite. The amounts of these sulfide minerals are poor, compared with those in epithermal Au-Ag vein-type deposits. It is noteworthy that silver minerals are abundant in epithermal Au-Ag vein-type deposits, whereas they are poor in gold-quartz veins. 

Ohta, E. (1992) Silver mineralization at the Toyoha mine, Hokkaido, Japan. Resource Geology, 42, 19-32. 

Sugaki, A., Isobe, K. and Kitakaze, A. (1982) Silver minerals from the Sanru mine. J. Assoc. Mineral Petrol and Econ. Geol, 77, 65-77 (in Japanese with English abst.). 

Sugaki, A., Kitakaze, A. and Isobe, K. (1986) Silver mineralization of the Karuizawa mine, Fukushima Prefecmre, Japan. Mining Geology, 36, 535-544. 

Yamaoka, K. and Nedachi, M. (1978b) Gold and silver minerals from Chitose and Takatama epithermal deposits. In Mining and Metallurgical Institute of Japan (ed.). Gold and silver ore in Japan, pp. 75-100 (in Japanese). 

Occurrence. Nearly all the silver ores are compounds of silver with sulphur and the neighbours in the Periodic Table arsenic, antimony and bismuth (argentite Ag2S, the most common silver compound, pyrargyrite Ag3SbS3, proustite Ag3AsS3). Other silver minerals include the halides. Silver is found sometimes as the free metal. Secondary silver (from catalysts, scraps, photographic films, etc.) is an important source. 

At the time when Vauquelin discovered iodine in a silver mineral from Mexico, M. del Rio, professor of mineralogy in our school of mines, confirmed the presence of the same substance in the horn silver of Albarradon. This latter name is that of a district near that of Mazapil, in the department of Zacatecas. The name of the mountain of Albarradon where the silver mine is located is Temeroso. 

When Berthier treated a specimen of this ore from the San Onofe Mine with an excess of hot ammonium hydroxide, he observed, mixed with the metallic silver, a green powder which had been only incompletely attacked. This was the circumstance, said he, which drew my attention to the ore from Plateros and which led me to realize that the substance which had been taken for silver chloride is pure bromide, without admixture of chloride or iodide, a substance which had not yet been met within the mineral realm and which therefore constitutes a new species (151). Berthier learned that this mineral is not rare in Mexico but is often found in beautiful cubic and octahedral crystals. He also found the same mineral at Huelgoeth, Department of Finistere, France, and discovered some of it among the Chilean silver minerals which Ignaz Domeyko, professor of chemistry at the College of Coquimbo, had sent to the School of Mines at Paris (151, 152). The mineral which Berthier analyzed was evidently bromyrite (silver bromide). 

MxtraeMon,—1. The silver minerals are roasted with sodio obloride, by which the metal is converted into chloride the mass is then mixed with water, scrap iron, and mercnry, ond ajptated for some hours. The iron reduces the argentic chloride to the metallic state, and the silver is then dissolved by the mercuiy. 

Argentite is probably die most important primary silver mineral. However, it maintains its cubic (isometric) characteristic only above 179 C (354°F). Upon cooling, the inward structure inverts to a noil-isometric form, usually orthorhombic, yet retaining its original outward form. It is, therefore, a paramorph after argentite, known as acanthite. 

PROUSTITE. This ruby-silver mineral crystallizes in the hexagonal system its name is a product of its scarlet-to-vermilion color when first mined It is a silver arsenic sulfide. AgjAsS, of adamantine luster Hardness of 2-2,5 specific gravity of 5.55-5.64. Usual crystal habit is prismatic to rhombohedral more commonly occurs massive. Conchoidal to uneven fracture transparent to translucent color, scarlet to vermilion red. Light sensitive must be kept in dark environment to maintain its primary character. A product of low-tcmpcraturc formation in most silver deposits. Notable world occurrences include the Czech Republic and Slovakia, Saxony, Chile and Mexico. Found in minor quantities in the United States the most exceptional occurrence at the Poorman Mine, Silver City District. Idaho where a crystalline mass of some 500 pounds (227 kilograms) was recovered m 1865, It was named for the famous French chemist, Louis Joseph Proust. 

Slephanite occurs associated with other silver minerals and is believed lo be primary in character. Localities are in ihe Czech Republic and Slovakia, Saxony, the Harz Mountains, Sardinia Cornwall, England Chile and Mexico, In the United States it is found in Nevada, where it is an important silver ore. It was named for the Archduke Stephan of Austria, mining director of that country at the time this mineral was first described. 

Drake HJ. 1980. Silver. Mineral facts and problems. Washington, DC U.S. Department of the interior, Bureau of Mines. Preprint from Bulletin 671. 

Oxygen is not needed for leaching of silver ores in which the silver is present as compounds a representative reaction for this case, for the silver mineral cerargyrite, AgCl, is... 

Oils,—These are of two kinds the collectors which have high affinities for sulphides and the frothers. Hard-wood creosote is the standard collective oil but owing to its expense other wood-, coal-, and oil-distillate products are substituted for it either entirely or in part, coal tar being a favorite. On silver minerals... 

Zierenberg, R.A. and Schiffman, P. (1990) Microbial control of silver mineralization at a sea-floor hydrothermal site on the northern Gorda Ridge. Nature, 348, 155-157. 

The publication of periodicals did not begin until the middle of the 19th century. In the Seminario de la Industria Mexicana appears "Electrochemistry, its progress and applications to Arts and Metallurgy" (1841 pp 55-59). Examples in the Sociedad Cientifica Antonio Alzate (1887-1920) concern the decomposition of salts etc., by the electric current (18), the electrochemistry of gold and silver minerals (19), electro-sinu-caustic surgery (20), industrial electrochemistry (21), and the theories of ions (22). —... 

In Mexico, ores are available containing pyragyrite and proustite, mined entirely for silver extraction, and Mexico derives 50% of its silver production from mines containing these so-called primary silver minerals The other half is, as in the rest of the world, a by-product of copper, zinc and lead production. 

---