Manganvesuvianite Locality: Wessels Mine (Wessel's Mine), Hotazel, Kalahari manganese fields, Northern Cape Province , South Africa ( Locality at mindat.org ) NOT a Gaudefroyite ! this one fooled us at first, too! It is a SUPERB mangan-vesuvianite with deep wine-red color when backlit, so you can be sure of the ID. This specimen features xls of the highest quality and the best lustre, almost glassy in brightness - rare for the species. There is some damage to smaller crystals, but most major crystals are complete, and the display is phenomenal. The matrix is sparkling, minutely crystallized andradite garnet. The large single crystal atop is doubly-terminated and almost 2 cm long tip to tip. 4.2 x 3.9 x 3.3 cm — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Manganvesuvianite
A rare red-to-black manganese-rich vesuvianite discovered in South Africa and described in 2002.
Intro adapted from Wikipedia (CC BY-SA).
Manganvesuvianite is an IMA-recognized mineral species in the silicate class, with the chemical formula Ca₁₉Mn³⁺Al₁₀Mg₂(SiO₄)₁₀(Si₂O₇)₄O(OH)₉.
It crystallizes in the tetragonal crystal system (space group P4/n). It is a member of the Vesuvianite structural group.
Key properties: Mohs hardness 6–7; specific gravity 3.404; Colorless streak; Vitreous luster; refractive index 1.73; optically uniaxial.
IMA symbol Mnves, IMA status: approved, named in 2000.
Found in calc-silicate lenses formed by hydrothermal alteration of primary sedimentary and low-grade metamorphic manganese ores.
It is found associated with Grossular, xonotlite, calcite, serandite-pectolite, strontiopiemontite-tweddillite, mozartite, hydrogrossular, henritermierite.
Prefix, mangan, indicates a vesuvianite group mineral with the five-coordinated (Y′) position occupied by Mn3+.