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| Stibnite | |
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| Stibnite in the Carnegie Museum of Natural History | |
| General | |
| Chemical formula | antimony sulfide (Sb2S3) |
| Identification | |
| Color | Steel gray to dull gray. Black iridescent tarnish may be present |
| Crystal habit | Massive, radiating and elongated crystals. Massive and granular |
| Crystal system | Orthorhombic |
| Cleavage | Perfect |
| Fracture | Small-scale subconchoidal |
| Mohs Scale hardness | 2 |
| Luster | Splendent on fresh crystals surfaces, otherwise metallic |
| Refractive index | Opaque |
| Streak | Similar to color |
| Specific gravity | 4.56–4.62 |
| Solubility | decomposed with hydrochloric acid |
| Major varieties | |
| Metastibnite | 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 metalloid antimony.1 The abbreviation for antimony, Sb, is taken from stibnite.
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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.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.[1]
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.citation needed
As of May 2007, the largest specimen on public display (1000 pounds) is at the American Museum of Natural History.34
See also
References
- ^ 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
- ^ Martin, T. M.; Schimek, G. L.; Pennington, W. T. and Kolis, J. W., "Synthesis of Two New Antimony Sulfide Clusters: Structures of [PPh42[Sb6S6 and [PPh42[Sb4S6", Journal of the Chemical Society, Dalton Transactions 1995, 501-2.
- ^ "American Museum of Natural History, Spectacular Stibnite". American Museum of Natural History. Retrieved on 2007-05-27.
- ^ 1000 Pound Stibnite!!
Wikipedia content modification information:
- This page was last modified on 31 December 2008, at 01:45.
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