AskDefine | Define sphalerite

Dictionary Definition

sphalerite n : an ore that is the chief source of zinc; consists largely of zinc sulfide in crystalline form [syn: zinc blende, blende]

User Contributed Dictionary

English

Etymology

From Greek σφαλερὀς (sfaledos) "treacherous", named in 1847.

Noun

  1. A yellow, brown or black, sometimes red, green white or colorless mineral with cubic crystals, of a chemical formula (Zn,Fe)S.

References

Extensive Definition

Sphalerite ((Zn,Fe)S) is a mineral that is the chief ore of zinc. It consists largely of zinc sulfide in crystalline form but almost always contains variable iron. When iron content is high it is an opaque black variety, marmatite. It is usually found in association with galena, pyrite, and other sulfides along with calcite, dolomite, and fluorite. Miners have also been known to refer to sphalerite as zinc blende, mock lead, false galena and black-jack.
The mineral crystallizes in the cubic crystal system. In the crystal structure, zinc and sulfur atoms are tetrahedrally coordinated. The structure is closely related to the structure of diamond. The hexagonal analog is known as the wurtzite structure. The lattice constant for zinc sulfide in the zincblende crystal structure is 0.596 nm, calculated from geometry and ionic radii of 0.074 nm (zinc) and 0.184 nm (sulfide). It forms ABCABC layers.
Its color is usually yellow, brown, or gray to gray-black, and it may be shiny or dull. Its luster is resinous. It has a yellow or light brown streak, a hardness of 3.5 - 4, and a specific gravity of 3.9-4.1. Some specimens have a red iridescence within the gray-black crystals; these are called "ruby sphalerite." The pale yellow and red varieties have very little iron and are translucent. The darker more opaque varieties contain more iron. Some specimens are also fluorescent in ultraviolet light. The refractive index of sphalerite (as measured via sodium light, 589.3 nm) is 2.37. Sphalerite crystallizes in the isometric crystal system and possesses perfect dodecahedral cleavage. Gemmy, pale specimens from Franklin, New Jersey (see Franklin Furnace) are highly fluorescent orange and/or blue under longwave ultraviolet light and are known as cleiophane, an almost pure ZnS variety.
Crystals of suitable size and transparency have been fashioned into gemstones, usually featuring the brilliant cut to best display sphalerite's high dispersion of 0.156 (B-G interval)—over three times that of diamond. Freshly cut gems are lively with an adamantine luster and could conceivably be mistaken for a fancy-colored diamond in passing, but due to sphalerite's softness and fragility the gems are best left unset as collector's or museum pieces (although some have been set into pendants). Collectors may pay a premium for stones over one carat (200 mg), as clean crystals are usually quite small. Gem-quality material is usually a yellowish to honey brown, red to orange, or green; the two most important sources are the Chivera mine, Cananea, Sonora, Mexico; and the Picos de Europa, Cordillera Cantabrica, near Santander on Spain's northern coast.

References

  • Dana's Manual of Mineralogy ISBN 0-471-03288-3
  • Webster, R., Read, P. G. (Ed.) (2000). Gems: Their sources, descriptions and identification (5th ed.), p. 386. Butterworth-Heinemann, Great Britain. ISBN 0-7506-1674-1
  • mindat.org
  • Minerals.net
  • Minerals of Franklin, NJ
sphalerite in Bosnian: Sfalerit
sphalerite in Catalan: Esfalerita
sphalerite in Czech: Sfalerit
sphalerite in German: Sphalerit
sphalerite in Spanish: Blenda
sphalerite in Persian: بلندروی
sphalerite in French: Sphalérite
sphalerite in Italian: Sfalerite
sphalerite in Hebrew: ספלריט
sphalerite in Latvian: Sfalerīts
sphalerite in Lithuanian: Sfaleritas
sphalerite in Hungarian: Szfalerit
sphalerite in Dutch: Zinkblende
sphalerite in Japanese: 閃亜鉛鉱
sphalerite in Norwegian: Sinkblende
sphalerite in Norwegian Nynorsk: Sinkblende
sphalerite in Low German: Sphalerit
sphalerite in Polish: Sfaleryt
sphalerite in Portuguese: Blenda
sphalerite in Romanian: Blendă
sphalerite in Russian: Сфалерит
sphalerite in Slovak: Sfalerit
sphalerite in Finnish: Sinkkivälke
sphalerite in Swedish: Zinkblände
sphalerite in Ukrainian: Сфалерит
sphalerite in Chinese: 閃鋅礦
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