Rhomboclase
Rhomboclase is an acidic iron sulfate mineral with a formula reported as H5Fe3+O2(SO4)2·2(H2O)[3] or HFe(SO4)2·4(H2O).[1] It crystallizes in the orthorhombic system and typically occurs as tabular crystals with a rhombic outline.[3] It occurs as transparent colorless, blue, green, yellow or grey crystals with a vitreous to pearly luster.[2]
| Rhomboclase | |
|---|---|
| General | |
| Category | Sulfate mineral |
| Formula (repeating unit) | H5Fe3+O2(SO4)2·2(H2O) |
| Strunz classification | 7.CB.55 |
| Crystal system | Orthorhombic |
| Crystal class | Dipyramidal (mmm) H-M symbol: (2/m 2/m 2/m) |
| Space group | Pnma |
| Identification | |
| Color | blue, colourless, white, yellow, light green, grey |
| Luster | sub-Vitreous, Pearly |
| Streak | white |
| Diaphaneity | transparent |
| References | [1][2] |
Rhomboclase forms within the oxidizing environment of pyrite rich ore deposits and is reported as a post mine mineral of arid regions.[3]
It was first described in 1888 for an occurrence in Slovakia and was named from Latin, rhombus, rhomb, and Greek klasis, to break, for its crystal form and perfect basal cleavage.[1]
References
- http://www.mindat.org/min-3410.html Mindat
- http://webmineral.com/data/Rhomboclase.shtml Webmineral data
- http://www.handbookofmineralogy.org/pdfs/rhomboclase.pdf Handbook of Mineralogy
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