Sturmanite

minerals

baryte

hausmannite

rhodochrosite

Formula: Ca6Fe3+2(SO4)2.5[B(OH)4](OH)12.25H2O
Compound sulphate, ettringite group
Specific gravity: 1.847
Hardness: 2½
Streak: Pale yellow, greenish yellow, brownish orange (altered)
Colour: Bright Yellow to amber
Environments

Metamorphic environments
Hydrothermal environments

Sturmanite is an uncommon secondary mineral occurring in cavities in metamorphosed bedded manganese deposits, associated with baryte, manganite, hausmannite and hematite (HOM).

Localities

At the type locality, the Black Rock mine, near Kuruman, Northern Cape, South Africa, sturmanite pseudomorphs after baryte and after gypsum have been found (KL p194, 195). Associated minerals include baryte and hematite (Dana).

At the NChwaning mine, Kalahari manganese fields, South Africa, rhodochrosite pseudomorphs after sturmanite have been found (KL p164).

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