Stibnite

Infobox mineral
name = Stibnite
category =
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caption = Stibnite in the Carnegie Museum of Natural History
formula = antimony sulfide (Sb₂S₃)
molweight =
color = Steel gray to dull gray. Black iridescent tarnish may be present
habit = Massive, radiating and elongated crystals. Massive and granular
system = Orthorhombic
twinning =
cleavage = Perfect
fracture = Small-scale subconchoidal
mohs = 2
luster = Splendent on fresh crystals surfaces, otherwise metallic
refractive = Opaque
opticalprop =
birefringence =
pleochroism =
streak = Similar to color
gravity = 4.56 - 4.62
melt =
fusibility =
diagnostic =
solubility = decomposed with hydrochloric acid
diaphaneity =
other =
var1 = Metastibnite | var1text = Earthy, reddish deposits

Stibnite, sometimes called antimonite, is a sulfide mineral with the formula Sb₂S₃. This soft grey material crystallizes in an orthorhombic space group. It is the most important source for the metaloid antimony. [Sabina C. Grund, K. Hanusch, H. J. Breunig, H. U. Wolf, “Antimony and Antimony Compounds” in Ullmann’s Encyclopedia of Industrial Chemistry 2006, Wiley-VCH, Weinheim. DOI|10.1002/14356007.a03 055.pub2] The abbreviation for antimony, Sb, is taken from stibnite.

Formation, structure, reactivity

Sb₂S₃ forms when antimony(III) compounds are treated with hydrogen sulfide. This reaction gives a black precipitate::2 Sb³⁺ + 3 H₂S → Sb₂S₃ + 6 H⁺This reaction is reversed by hydrochloric acid.

Stibnite is attacked by potassium hydroxide solution and dissolves in solutions of polysulfide ions to give polysulfido complexes. [Martin, T. M.; Schimek, G. L.; Pennington, W. T. and Kolis, J. W., "Synthesis of Two New Antimony Sulfide Clusters: Structures of [PPh₄] ₂ [Sb₆S₆] and [PPh₄] ₂ [Sb₄S₆] ", Journal of the Chemical Society, Dalton Transactions 1995, 501-2.] Related reactions were once used in university courses on qualitative inorganic analysis.

Stibnite has a structure similar to that of arsenic trisulfide, As₂S₃. The Sb(III) centers, which are pyramidal and three-coordinate, are linked via bent two-coordinate sulfide ions.

Uses

Stibnite has no significant uses, except as a precursor to antimony oxide, which is the most commonly marketed form of antimony. In ancient times, it was used as mascara called kohl.

Antimony trisulfide finds use in pyrotechnic compositions, namely in the glitter and fountain mixtures. Needle-like crystals, "Chinese Needle", are used in glitter compositions and white pyrotechnic stars. The "Dark Pyro" version is used in flash powders to increase their sensitivity and sharpen their report. It is also a component of modern safety matches. It was formerly used in flash compositions, but its use was abandoned due to toxicity and sensitivity to static electricity. [http://www.pyrouniverse.com/chem.htm]

Occurrence

Small deposits of stibnite are common, but large deposits are rare. It occurs in Canada, Mexico, Peru, Japan, China, Germany, Romania, Italy, France, England, Algeria, and Kalimantan, Borneo. In the United States it is found in Arkansas, Idaho, Nevada, California, and Alaska. Large iridescent stibnite crystals are found in Japan.Fact|date=May 2007

As of May 2007, the largest specimen on public display (1000 pounds) is at the American Museum of Natural History. [cite web| url =http://www.amnh.org/science/papers/stibnite.php | title=American Museum of Natural History, Spectacular Stibnite| publisher=American Museum of Natural History|accessdate=2007-05-27] [ [http://www.cctv.com/program/cultureexpress/20070406/100505.shtml 1000 Pound Stibnite!!] ]

See also

* List of minerals

References