sphalerite


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sphalerite

(sfăl`ərīt, sfā`–), mineral composed of zinc sulfide, usually containing some iron and a little cadmium. It occurs in crystals of the isometric system but more generally in cleavable, compact masses. It is transparent to translucent and varies greatly in color, iron-free specimens being pale yellow and those with iron being brown, red, black, or green. The most important source of zinczinc,
metallic chemical element; symbol Zn; at. no. 30; at. wt. 65.38; m.p. 419.58°C;; b.p. 907°C;; sp. gr. 7.133 at 25°C;; valence +2. Zinc is a lustrous bluish-white metal. It is found in Group 12 of the periodic table.
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, sphalerite is a widely distributed mineral that commonly occurs in association with galena. It is found in large deposits in many parts of the world.

Sphalerite

 

(also blende), a mineral of the sulfide class with the chemical composition ZnS (67.1 percent Zn and 32.9 percent S). Sphalerite contains isomorphous admixtures of Fe (up to 26 percent), Mn, Cd, Ga, Ge, In, Co, and Hg. Varieties rich in Fe are known as marmatite, while the colorless and nearly colorless varieties are known as cleiophane. The structure of sphalerite is one of very dense cubic packing of S atoms with the tetrahedral interstices occupied by Zn atoms. The hexagonal modification of ZnS is called wurtzite. Certain sphalerites occur as banded inter-growths of cubic and hexagonal polytypic varieties.

Sphalerite occurs as granular masses, and the mineral frequently forms tetrahedral or dodecahedral crystals. In the absence of admixtures, it is colorless. The variations in color between brown and black are explained by the content of Fe. If Fe is present in small quantities, the greenish yellow color is caused by Cd, and the red color by Mn, Cu, and Ag and by In and Tl. Sphalerite has an adamantine luster, a hardness on Mohs’ scale of 3.5–1.0, and a density of 3,900–4,100 kg/m3, and it possesses piezoelectric and pyroelectric properties. It is formed in hydrothermal deposits together with galena, pyrite, chalcopyrite, arseno-pyrite, quartz, calcite, barite, and dolomite and in sedimentary deposits. In the zone of oxidation, sphalerite alters to zinc sulfate (goslarite) and smithsonite. Sphalerite is an important zinc ore.

A. S. MARFUNIN

sphalerite

[′sfal·ə‚rīt]
(mineralogy)
(Zn,Fe)S The low-temperature form and common polymorph of zinc sulfide; a usually brown or black mineral that crystallizes in the hextetrahedral class of the isometric system, occurs most commonly in coarse to fine, granular, cleanable masses, has resinous luster, hardness of 3.5 on Mohs scale, and specific gravity of 4.1. Also known as blende; false galena; jack; lead marcasite; mock lead; mock ore; pseudogalena; steel jack.
References in periodicals archive ?
In most primary ore deposits, galena (PbS) and sphalerite (ZnS) are the common minerals of lead and zinc, respectively.
At some places, the intergrowth textures between the various phases, especially tetrahedrite, galena, chalcopyrite and sphalerite suggest a simultaneous crystallization of these phases from the hydrothermal solutions.
All four mines exploit stratabound sphalerite deposits in Precambrian metasediments.
In the early 1900s an Elmore flotation plant was installed so that galena, sphalerite and barite could be separated.
SRCD064 (section 1120N) drilled on the same section and 100m below SRCD063, intersected 34m of massive chalcopyrite, sphalerite and pyrite from 393.
Zone Two is composed of massive to semi-massive pyrite and sphalerite with well developed banded and fragmental textures.
Primary silver mineralization occurs with sphalerite, galena and pyrite in veinlets and in the matrix of a brecciated rhyolite.
The district became famous for spectacular examples of calcite (in crystals measuring up to 5 feet long), galena and sphalerite.
The black matrix breccia contained minor disseminated pyrite and trace sphalerite while the Ballysteen Limestone contained larger amounts of pyrite.
TSX VENTURE:SUV) is pleased to announce the acquisition by staking from the Government of Alberta -- 230,400 acres (93,242 hectares) north of Zama Lake, Alberta, to cover part of an anomalous train of sphalerite (Zinc) and galena (Lead) grains in soils disclosed in a recently released Geological Survey of Canada (GSC) Open File #5121/Alberta Geological Survey (AGS) SPE-77 on March 1st, 2006.
During the 25 years of mining, tens of thousands of wonderful specimens of calcite, fluorite, sphalerite, barite and galena found their way to the mineral market.
The upper veins and fractures have been found to contain abundant galena, sphalerite, and tetrahedrite together with quartz and barite gangue.