Acuminite
Acuminite is a rare halide mineral of with chemical formula: SrAlF4(OH)·(H2O). Its name comes from the Latin word acumen, meaning "spear point". Its Mohs scale rating is 3.5.
| Acuminite | |
|---|---|
| General | |
| Category | Halide mineral |
| Formula (repeating unit) | SrAlF4OH·(H2O) |
| Strunz classification | 3.CC.10 |
| Crystal system | Monoclinic |
| Crystal class | Prismatic (2/m) (same H-M symbol) |
| Space group | C2/c |
| Unit cell | a = 13.223, b = 5.175 c = 14.251 [Å]; β = 11.61°; Z = 8 |
| Identification | |
| Color | White |
| Crystal habit | Clusters of acute dipyramidal Spearhead shaped crystals |
| Twinning | Contact on {100} |
| Cleavage | Perfect on {001} |
| Mohs scale hardness | 3.5 |
| Luster | Vitreous |
| Diaphaneity | Transparent |
| Specific gravity | 3.295 |
| Optical properties | Biaxial (+) |
| Refractive index | nα = 1.451 nβ = 1.453 nγ = 1.462 - 1.463 |
| References | [1][2][3] |
Acumenite has only been described from its type locality of the cryolite deposit in Ivigtut, Greenland.[1]
References
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Look up acuminite in Wiktionary, the free dictionary. |
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