Stibnite
| Stibnite | |
|---|---|
Stibnite
|
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| General | |
| Category | Sulfide mineral |
|
Formula (repeating unit) |
Sb2S3 |
| Strunz classification | 2.DB.05a |
| Crystal system | Orthorhombic |
| Crystal class | Dipyramidal (mmm) H-M symbol: (2/m 2/m 2/m) |
| Space group | Pbnm |
| Unit cell | a = 11.229 Å, b = 11.31 Å, c = 3.8389 Å; Z = 4 |
| Identification | |
| Color | Lead-gray, tarnishing blackish or iridescent; in polished section, white |
| Crystal habit | Massive, radiating and elongated crystals. Massive and granular |
| Twinning | Rare |
| Cleavage | Perfect and easy on {010}; imperfect on {100} and {110} |
| Fracture | Subconchoidal |
| Tenacity | Highly flexible but not elastic; slightly sectile |
| Mohs scale hardness | 2 |
| Luster | Splendent on fresh crystals surfaces, otherwise metallic |
| Streak | Similar to color |
| Diaphaneity | Opaque |
| Specific gravity | 4.63 |
| Solubility | decomposed with hydrochloric acid |
| Other characteristics | Anisotropism: Strong |
| References | |
| 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. The name is from the Greek στίβι stibi through the Latin stibium as the old name for the mineral and the element antimony.
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. However, recent studies confirm that the actual coordination polyhedra of antimony are in fact SbS7, with (3+4) coordination at the M1 site and (5+2) at the M2 site. Some of the secondary bonds impart cohesion and are connected with packing. Stibnite is grey when fresh, but can turn superficially black due to oxidation in air.
Pastes of Sb2S3 powder in fat or in other materials have been used since ca. 3000 BC as eye cosmetics in the Middle East and farther afield; in this use, Sb2S3 is called kohl. It was used to darken the brows and lashes, or to draw a line around the perimeter of the eye.
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.
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Wikipedia