Schallerite

schallerite

nelenite

pyroxmangite

tephroite

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Formula: Mn²⁺₁₆As³⁺₃Si₁₂O₃₆(OH)₁₇
Phyllosilicate (sheet silicate), pyrosmalite group, manganese-bearing mineral
Crystal System: Trigonal
Specific gravity: 3.37 measured, 3.45 calculated
Hardness: 4½ to 5
Streak: Pale brown
Colour: Light brown, reddish brown
Common impurities: Ti,Al,Zn,Mg,Ca,Cl,H₂O
Environments:

Metamorphic environments

Schallerite is a rare arsenic mineral, paramorphous 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, (Dana, Mindat) associated with willemite, franklinite, calcite and rhodonite (HOM).

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 (HOM).

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