Arsenic sulfides minerals

Nickel [7440-02-0] Ni, recognized as an element as early as 1754 (1), was not isolated until 1820 (2). It was mined from arsenic sulfide mineral deposits (3) and first used in an alloy called German Silver (4). Soon after, nickel was used as an anode in solutions of nickel sulfate [7786-81 A] NiSO, and nickel chloride [7718-54-9] NiCl, to electroplate jewelry. Nickel carbonyl [13463-39-3] Ni(C02)4, was discovered in 1890 (see Carbonyls). This material, distilled as a hquid, decomposes into carbon monoxide and pure nickel powder, a method used in nickel refining (5) (see Nickel and nickel alloys). 

Cline, J.S. (2001) Timing of gold and arsenic sulfide mineral deposition at the Getchell Carlin-type gold deposit, north-central Nevada. Economic Geology, 96(1), 75-89. 

Claudetite and arsenolite are products of weathering of several arsenic sulfide minerals, of native arsenic, and of scorodite. 

Dimorphite (or dimorphine ) is a soft, yeUow-orange orthorhombic arsenic sulfide mineral. It has chemical composition AS4S3 and forms by deposition from volcanic hot gas vents (Hey, 1993). Whitfield (1970) has reported the synthesis of two crystalline forms (Type 1 and Type 11). Dimorphite is found in volcanic areas such as Attica, Greece and Vesuvius, Italy, where it can occur in association with the arsenic sulfide minerals, orpiment and realgar it is also closely related to other arsenic sulfide minerals duransite and alacranite (qq.v.). 

The magnetic criterion is particularly valuable because it provides a basis for differentiating sharply between essentially ionic and essentially electron-pair bonds Experimental data have as yet been obtained for only a few of the interesting compounds, but these indicate that oxides and fluorides of most metals are ionic. Electron-pair bonds are formed by most of the transition elements with sulfur, selenium, tellurium, phosphorus, arsenic and antimony, as in the sulfide minerals (pyrite, molybdenite, skutterudite, etc.). The halogens other than fluorine form electron-pair bonds with metals of the palladium and platinum groups and sometimes, but not always, with iron-group metals. 

Antimony was known in the days of alchemy (500 BCE to 1600 ce) when it was associated with other metals and minerals such as arsenic, sulfides, and lead used as medications. It is possible that an alchemist, Basilus Valentinus (fi. 1450), knew about antimony and some of its minerals and compounds sometime around the mid-fifteenth century ce. Physicians of this period—and earlier periods—used elements such as mercury and antimony to cure diseases, although they knew that these elements were toxic in larger doses. Antimony was used to treat depression, as a laxative, and as an emetic for over two thousand years. Despite the elements poisonous nature, physicians of that early era considered both mercury and antimony good medicines. 

The volcanic sublimates ", such as sulfur, ammonium chloride, arsenic sulfide, copper chloride, magnetite, may be mentioned in this connection, as well as the minerals accompanying fumarole and hot-spring activity. 

Arsenic sulfide occurs in nature as the mineral realgar. It is used as a pigment in pyrotechnics to produce blue fire in dyeing and calico printing and as a depilatory for hides. 

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. 

Factors influencing the oxidation of arsenic-bearing sulfide minerals... 

Many factors affect the oxidation rates of sulfide minerals and the chemistry of their oxidation products. A few of the important factors are briefly introduced in this section and discussed in further detail in this and later chapters. As a result of the complex interactions between these different factors, high-arsenic rocks and mining wastes will not automatically produce high-arsenic weathering products and aqueous solutions (Piske, 1990). 

Temperature, humidity, precipitation, and evaporation are important factors that contribute to the oxidation of sulfide minerals. In warm and wet climates, excessive precipitation may produce persistently high water tables and extensive biological activity that may create reducing conditions in the shallow subsurface and hinder sulfide oxidation (Seal et al., 2002, 208). At the surface, high humidity and temperatures would promote the oxidation of sulfide minerals (Williams, 2001, 274). Frequent precipitation would also suppress evaporation and the formation of arsenic salt deposits (Seal et al., 2002, 208). Furthermore, precipitation and groundwater, which are controlled by climate, are the major sources of water for the production of arsenic-contaminated runoff from sulfide-bearing rock outcrops. 

Pyrite is the most common sulfide mineral. It is a major contributor to the formation of mine drainage and sulfate-rich natural runoff. The oxidation of pyrite and other Fe(II) sulfides (e.g. marcasite and pyrrhotite) involves both iron and sulfur, as well as any arsenic impurities. Activation energies suggest that surface reactions dominate the oxidation of pyrite (Lengke and Tempel, 2005). Furthermore, evidence from pyrites in coal and ore deposits suggests that arsenian pyrite is more susceptible to oxidation from weathering than low-arsenic pyrite (Savage et al., 2000, 1239). 

In some circumstances, the oxidation of sulfide minerals to sulfate (oxy)(hydr)oxides involves one or more intermediate steps that are related to the properties of the field location. For example, realgar and orpiment in mining wastes at the Kusa mine in Sarawak, Malaysia, initially weather to arsenolite. The arsenolite readily dissolves in sulfate-rich waters in open pits. As the water evaporates, arsenic-rich jarosite precipitates (Williams, 2001, 274). 

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