Adelite
The rare mineral adelite, is a calcium, magnesium, arsenate with chemical formula CaMgAsO4OH. It forms a solid solution series with the vanadium-bearing mineral gottlobite. Various transition metals substitute for magnesium and lead replaces calcium leading to a variety of similar minerals in the adelite–duftite group.
| Adelite | |
|---|---|
Pinkish crystal aggregates of adelite from the Franklin deposit in Ogdensburg, New Jersey | |
| General | |
| Category | Adelite-descloizite group |
| Formula (repeating unit) | CaMg(AsO4)(OH) |
| IMA symbol | Ade |
| Strunz classification | 8.BH.35 |
| Dana classification | 41.5.1.1 |
| Crystal system | Orthorhombic |
| Crystal class | 2 2 2 – Disphenoidal |
| Space group | P212121 |
| Identification | |
| Color | Colourless, white, grey, bluish grey, yellowish grey, yellow, pale green, pinkish brown, brown |
| Crystal habit | Elongate crystals, massive |
| Cleavage | None observed |
| Mohs scale hardness | 5 |
| Luster | Vitreous, greasy |
| Diaphaneity | Transparent, translucent |
| Specific gravity | 3.73 to 3.79 |
| Optical properties | Biaxial (+), colorless (transmitted light) |
| References | |
Adelite forms variably colored (blue, green, yellow and grey) crystals in the orthorhombic crystal system. The form is typically massive. It has a Mohs hardness rating of 5 and a specific gravity of 3.73 to 3.79.
It was first described in 1891 from Värmland, Sweden. Its name comes from the Greek word for indistinct.
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