Manganvesuvianite

manganvesuvianite

xonotlite

serandite

pectolite

Images

Formula: Ca19Mn3+Al10Mg2(SiO4)10(Si2O7)4O(OH)9
Sorosilicate (Si2O7 groups), vesuvianite group
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).

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