Schallerite

phyllosilicate

manganese

Formula: Mn2+16As3+3Si12O36(OH)17
Phyllosilicate (sheet silicate), pyrosmalite group
Specific gravity: 3.37
Hardness: 4½ to 5
Streak: Pale brown
Colour: Light brown, reddish brown
Environments:

Metamorphic environments

Schallerite is a rare arsenic mineral, dimorphous with nelenite.

At the type locality, the Franklin mine New Jersey, USA, schallerite is found with calcite in fractures perpendicular to banded willemite-franklinite ore, and as aggregates in massive rhodonite, associated with willemite, franklinite, calcite and rhodonite.

At the Kaodnitz valley, Austria, schallerite occurs in manganese-rich lenses in quartzitic chlorite schist, probably of marine origin, associated with tephroite, pyroxmangite, rhodonite, spessartine and rhodochrosite.

Common impurities: Ti,Al,Zn,Mg,Ca,Cl,H2O

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