Arsenopyrite: Difference between revisions
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Various [[transition]] group metals occur in arsenopyrite as subtitutes for iron. A [[cobalt]] rich variety is known as danaite, named after [[James Dana]] the famous American mineralogist. |
Various [[transition]] group metals occur in arsenopyrite as subtitutes for iron. A [[cobalt]] rich variety is known as danaite, named after [[James Dana]] the famous American mineralogist. |
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Arsenopyrite also can contain significant amounts of [[gold]] and consequently is used by geologists as an indicator of potential gold bearing reefs. Many arsenopyrite gold ores are [[refractory], the gold unable to be easily liberated from the arsenopyrite matrix. |
Arsenopyrite also can contain significant amounts of [[gold]] and consequently is used by geologists as an indicator of potential gold bearing reefs. Many arsenopyrite gold ores are [[refractory]], the gold unable to be easily liberated from the arsenopyrite matrix. |
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Arsenopyrite is found in high temperature [[hydrothermal]] veins, in [[pegmatite]]s, and in areas of contact [[metamorphism]] or [[metasomatism]]. |
Arsenopyrite is found in high temperature [[hydrothermal]] veins, in [[pegmatite]]s, and in areas of contact [[metamorphism]] or [[metasomatism]]. |
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Revision as of 04:08, 23 March 2006
| Arseonpyrite | |
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| General | |
| Category | Mineral |
| Chemical formula | AsFeS |
| Identification | |
| Colour | Steel grey to silver |
| Crystal habit | Acicular, off-square prismatic, stubby or massive; striated |
| Crystal system | monoclinic; ?/m ?/m ?/m |
| Cleavage | 110 (distinct) |
| Fracture | Subconchoidal to rough |
| Mohs Scale hardness | 5.5 - 6 |
| Luster | Metallic |
| Refractive index | Opaque |
| Pleochroism | None |
| Streak | Black |
| Specific gravity | 5.9 - 6.2 |
| Fusibility | Yes |
| Solubility | Nitric acid |
| Other | Garlic odour when struck, greenish tinge when weathered, green staining of wall rocks |
Arsenopyrite is an iron arsenic sulfide (FeAsS). It is a hard (Moh's 5.5-6) metallic, opaque, steel grey to silver white mineral with a relatively high specific gravity of 6.1. When dissolved in nitric acid, it produces sulfur. When arsenopyrite is heated, it becomes magnetic, and gives off toxic fumes.
Arsenopyrite contains about 46% arsenic and is a principle ore of arsenic along with orpiment.
Arsenopyrite crystallizes in the monoclinic crystal system and often shows prismatic crystal or columnar forms with striations and twinning common. Arsenopyrite may be referred to in older references as orthorhombic, but has been shown to be monoclinic.
The crystal habit, hardness, density, and garlic odor when struck are diagnostic. Arsenopyrite in older literature may be referred to as mispickle, an allusion to the odour of sulfurous bacteria in failed attempts at pickling, which is reminiscent of the odour of arsenopyrite when struck.
Various transition group metals occur in arsenopyrite as subtitutes for iron. A cobalt rich variety is known as danaite, named after James Dana the famous American mineralogist.
Arsenopyrite also can contain significant amounts of gold and consequently is used by geologists as an indicator of potential gold bearing reefs. Many arsenopyrite gold ores are refractory, the gold unable to be easily liberated from the arsenopyrite matrix.
Arsenopyrite is found in high temperature hydrothermal veins, in pegmatites, and in areas of contact metamorphism or metasomatism.
The arsenopyrite group of minerals includes the following rare minerals:
- Clinosafflorite: (Co,Fe,Ni)AsS
- Gudmundite: FeSbS
- Glaucodot, Danaite, or Alloclasite: (Fe,Co)AsS
- Iridarsenite: (Ir,Ru)AsS
- Osarsite or Ruarsite: (Os,Ru)AsS or (Ru,Os)AsS
References
- Hurlbut, Cornelius S.; Klein, Cornelis, 1985, Manual of Mineralogy, 20th ed., ISBN 0471805807
- mindat.org
- Minerals.net