Metacinnabar
Metacinnabar is the cubic form of mercury sulfide (HgS). It is the low temperature form and trimorphous with cinnabar (trigonal structure) and the high temperature hypercinnabar (hexagonal structure). It occurs with cinnabar in mercury deposits and is associated with native mercury, wurtzite, stibnite, marcasite, realgar, calcite, barite, chalcedony and hydrocarbons.[1]
| Metacinnabar | |
|---|---|
 | |
| General | |
| Category | Sulfide mineral |
| Formula (repeating unit) | HgS |
| Strunz classification | 2.CB.05a |
| Crystal system | Cubic |
| Crystal class | Hextetrahedral (43m) H-M symbol: (4 3m) |
| Space group | F43m |
| Unit cell | a = 5.8717(5) Å; Z = 4 |
| Structure | |
| Jmol (3D) | Interactive image |
| Identification | |
| Color | Grayish black |
| Crystal habit | Massive, rarely as tetrahedral crystals, as incrustations |
| Twinning | Common as lamellae on {111} |
| Cleavage | None |
| Fracture | Subconchoidal |
| Tenacity | Brittle |
| Mohs scale hardness | 3 |
| Luster | Metallic |
| Streak | Black |
| Diaphaneity | Opaque |
| Specific gravity | 7.7 - 7.8 |
| References | [1][2][3] |
It was first described in 1870 for an occurrence in the Redington mine, Knoxville, Napa County, California.[2][3]
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