Manganvesuvianite
From Wikipedia, the free encyclopedia
| Manganvesuvianite | |
|---|---|
 Manganvesuvianite from Wessels Mine, Northern Cape Province, South Africa (4.2 x 3.9 x 3.3 cm) | |
| General | |
| Category | Sorosilicates |
| Formula | Ca19Mn3+(Al,Mn3+,Fe3+)10(Mg,Mn2+)2(Si2O7)4(SiO4)10O(OH)9 |
| IMA symbol | Mnves[1] |
| Strunz classification | 9.BG.35 |
| Dana classification | 58.02.04.04[2] |
| Crystal system | Tetragonal |
| Crystal class | Dipyramidal (4/m) (same H-M symbol) |
| Space group | P4/n |
| Unit cell | a = 15.575 Å, c = 11.824 Å, Z = 2 |
| Identification | |
| Color | Deep red-brown, red, nearly black |
| Cleavage | None observed |
| Fracture | Conchoidal |
| Mohs scale hardness | 6 to 7 |
| Luster | Vitreous |
| Streak | White |
| Diaphaneity | Transparent, translucent, opaque |
| Optical properties | Uniaxial (-) |
| Refractive index | nω = 1.735, nε = 1.724 |
| Birefringence | δ = 0.012 |
| Pleochroism | Strong |
| References | [3] |
Manganvesuvianite is a rare mineral with formula Ca19Mn3+(Al,Mn3+,Fe3+)10(Mg,Mn2+)2(Si2O7)4(SiO4)10O(OH)9. The mineral is red to nearly black in color. Discovered in South Africa and described in 2002, it was so named for the prevalence of manganese in its composition and its relation to vesuvianite.
Manganvesuvianite crystals occur as long prisms up to 1.5 cm (0.59 in).[4] Small crystals are transparent and red to lilac in color; large crystals are opaque and nearly black in color with dark-red internal reflections.[5] Strongly zoned crystals less than 0.2 mm (0.0079 in) in size constitute rock-forming manganvesuvianite.[6]
As of 2012[update], manganvesuvianite has been found at two locations in South Africa.[3] It formed at temperatures of 250 to 400 °C (482 to 752 °F) by the hydrothermal alteration of sedimentary and metamorphic manganese ores. Crystallization occurred in fault planes and lenticular bodies in the ore bed or by filling veins and vugs.[7] Manganvesuvianite has been found in association with calcite, manganese-poor grossular, hydrogrossular-henritermierite, mozartite, serandite-pectolite, strontiopiemontite-tweddillite, and xonotlite.[8]
Manganvesuvianite is a member of the vesuvianite group and is the manganese analogue of vesuvianite.[3]
