Roscoelite
Roscoelite is a green mineral from the mica group that contains vanadium.
| Roscoelite | |
|---|---|
Roscoelite and gold | |
| General | |
| Category | Phyllosilicate |
| Formula (repeating unit) | K(V3+,Al,Mg)2AlSi3O10(OH)2 |
| IMA symbol | Rcl |
| Strunz classification | 9.EC.15 |
| Crystal system | Monoclinic |
| Crystal class | Prismatic (2/m) (same H-M symbol) |
| Space group | C2/m |
| Identification | |
| Formula mass | 426.53 g/mol |
| Colour | olive-green to green-brown |
| Crystal habit | scales, fans, druses, rosettes, fibrous or felted aggregate. |
| Cleavage | Perfect plane {0,0,1} |
| Fracture | platy |
| Mohs scale hardness | 1 |
| Lustre | pearly |
| Diaphaneity | semi-transparent to translucent |
| Specific gravity | 2.92 - 2.96 |
| Optical properties | Biaxial (-) |
| Refractive index | nα=1.60 nβ=1.66 nγ=1.67 |
| Birefringence | δ = |
| Pleochroism | olive green to green-brown |
| Fusibility | loses water |
The chemical formula is K(V3+, Al, Mg)2AlSi3O10(OH)2. Crystals of roscoelite take on the monoclinic form, and are from the 2/m point group. The appearance is semi transparent to translucent coloured olive brown to green brown. The lustre is pearly. The mineral shows pleochroism with X showing green-brown, and Y and Z axes showing olive-green colour. The mineral was named after Henry Enfield Roscoe who first produced vanadium metal.
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