Greenockite

Greenockite, see Cadmium sulfide Gruenerite, see Iron(II) silicate(2—)... 

Naturally occurring cadmium compounds are limited to the rare minerals, greenockite [1317-58 ] CdS, and otavite (1), an oxycarbonate, but neither is an economically important source of cadmium metal or its compounds. Instead, cadmium compounds are more usually derived from metallic cadmium [7440-43-9] which is produced as a by-product of lead—2inc smelting or electrolysis (see Cadmiumand cadmium alloys). Typically, this cadmium metal is burnt as a vapor, to produce the brown-black cadmium oxide [1306-19-0], CdO, which then acts as a convenient starting material for most of the economically important compounds. 

A similar distortion may occur in some crystals with the wurtzite structure. Wurtzite and greenockite show easy prismatic cleavage and difficult basal cleavage, whereas iodyrite, Agl, cleaves perfectly on the... 

Minerals dominated by cadmium are rare the sulfide CdS (greenockite), especially, is very rarely found. However, cadmium is widespread in zinc ores in low concentrations (0.2-0.4%) and is separated during processing of these ores and production of zinc. 

Greenockite ore, as well as zinc and other ores, which produce cadmium as a by-product, are found in many countries, including Australia, Mexico, Peru, Zaire, Canada, Korea, and Belgium-Luxembourg and in the central and western United States. 

Cadmium sulfide [68859-25-6], CdS, Mr 144.48, occurs as greenockite or cadmium-blende in several natural deposits, which are, however, of no importance as pigments. The mineral crystallizes hexagonally in the wurtzite lattice (a-form). 

Although ranking 57th in abundance in the earth s crust tO. 15 ppm), cadmium is not encountered alone, but is always associated with zinc. The only known cadmium minerals are greenockite (sulfide) and otavite (carbonate), both minor constituents of sphalerite (zinc oxide) and smilhsoniie (zinc carbonate), respectively See also Greenockite Smithsonite and Sphalerite Blende. 

Cadmium, Cd, at wt 112.4 soft blue-wh malleable metal or grayish- wh powd d 8.642 at 17°, mp 320.9°, bp 767° insol in w sol in acids and AN solns occurs chiefly as greenockite (CdS) associated with Zn(or Pb) manuf. Its toxicity is discussed by Sax(Ref 3). Fire and expln hazards are slight when Cd dust is exposed to heat or flame(Ref 3)... 

The mineral greenockite (CdS) occurs in nature mixed with sphalerite. 

Uses Cadmium (Cd) (L. cadmia Gr. kadmeia, ancient name for calamine, zinc carbonate) was discovered by Stromeyer in 1817 through an impurity in zinc carbonate. Cadmium most often occurs in small quantities associated with zinc ores, such as sphalerite (ZnS). The important compounds used in industry are cadmium oxide (CdO), cadmium chloride (CdCl2), cadmium nitrate (CdfNCRh), cadmium sulfide (CdS), and cadmium sulfate (CdSC>4). Greenockite (CdS) is the only mineral of any consequence bearing cadmium. Cadmium is also obtained as a by-product in the treatment of zinc, copper, nonferrous metal industry, and lead ores. Cadmium is a highly toxic heavy metal that forms complex compounds with other metals and elements. 

Early attempts to prepare low-melting alloys with cadmium sulfide (its natural form, greenockite, is orange-yellow) encouraged further investigation... 

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