Vanadiocarpholite
Vanadiocarpholite (Mn+2V+3AlSi2O6(OH)4) is straw yellow to brown silicate mineral. It crystallizes in the orthorhombic crystal system. It is the vanadium rich variety of carpholite (Mn+2Al2Si2O6(OH)4).
| Vanadiocarpholite | |
|---|---|
| General | |
| Category | Silicate mineral |
| Formula (repeating unit) | Mn+2V+3AlSi2O6(OH)4 |
| Strunz classification | 9.DB.05 |
| Crystal system | Orthorhombic |
| Crystal class | Dipyramidal (mmm) H-M symbol: (2/m 2/m 2/m) |
| Space group | Ccca |
| Unit cell | a = 13.83 Å, b = 20.681 Å c = 5.188 Å; Z = 8 |
| Identification | |
| Color | Pale-straw yellow, honey-yellow to brown |
| Crystal habit | Prismatic to acicular crystal clusters, vein fillings |
| Cleavage | Perfect on {010} |
| Tenacity | Flexible |
| Luster | Vitreous, silky |
| Diaphaneity | Transparent |
| Optical properties | Biaxial (+) |
| Refractive index | nα=1.684, nβ=1.691, nγ=1.7 |
| Birefringence | 0.0160 |
| References | [1][2] |
Discovery and occurrence
It was first described in 2005 for an occurrence in the Molinello Mine, Graveglia Valley, Genova Province, Liguria, Italy.[2] It occurs in chert in a manganese ore deposit as vein fillings in silicified wood.[1]
Chemical composition
It consists of:[1]
| Manganese | 15.56% | Mn | 20.09% | MnO |
| Aluminium | 7.64% | Al | 14.44% | Al2O3 |
| Vanadium | 14.43% | V | 21.23% | V2O3 |
| Silicon | 15.91% | Si | 34.04% | SiO2 |
| Hydrogen | 1.14% | H | 10.21% | H2O |
| Oxygen | 45.32% | O |
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