Images
Formula:
Ca19Mn3+Al10Mg2(SiO4)10(Si2O7)4O(OH)9
Sorosilicate (Si2O7 groups),
vesuvianite group,
manganese-bearing mineral
Crystal System: Tetragonal
Specific gravity: 3.404 calculated
Hardness: 6 to 7
Streak: White
Colour: Deep red-brown, red, nearly black
Environments
Sedimentary environments
Metamorphic environments
Hydrothermal environments
Manganvesuvianite is found in calc-silicate lenses formed
by hydrothermal alteration of primary sedimentary and
low-grade metamorphic manganese ores. Associated minerals include
grossular, xonotlite,
calcite,
serandite-pectolite,
piemontite-(Sr)-tweddillite,
mozartite, hydrogrossular
and henritermierite
(HOM).
Localities
At the type locality, the N'Chwaning II Mine, N'Chwaning Mines, Kuruman, Kalahari manganese field, Northern Cape,
South Africa, and at the Wessels Mine, Hotazel, also in the Kalahari manganese field, manganvesuvianite
was formed by hydrothermal alteration at 250°to 400°C of primary sedimentary and low-grade
metamorphic ores, which created mineralised zones as veins and vug linings or along fault planes and lenses
within the manganese ore beds. The manganvesuvianite occurs as
prismatic crystals up to 1.5 cm long filling veins and vugs. Larger crystals are nearly black and opaque with
dark red internal reflections, smaller crystals are red to lilac and transparent. At the N’Chwaning II mine,
manganvesuvianite is also rock-forming, densely intergrown with either
manganese-poor grossular
or xonotlite and calcite in
lenticular calc-silicate bodies within the
manganese ore beds. Additional associated minerals include
serandite-pectolite,
piemontite-(Sr)-tweddillite,
mozartite,
hydrogrossular
and henritermierite.
(MM 66.137-150, R&M 85-2.146).
Back to Minerals