Zwieselite

minerals

triplite

triphylite

rockbridgeite

Formula: Fe2+2(PO4)F
Anhydrous phosphate containing halogen, triplite group, and forms a series with it
Specific gravity: 3.89 to 3.97
Hardness: 5 to 5½
Streak: White to tan
Colour: Dark brown, black (altered)
Solubility:
Common impurities: Mg,Ca
Environments

Pegmatites

Zwieselite occurs as a primary phosphate in complex zoned granite pegmatites, associated with triphylite, hureaulite and rockbridgeite (HOM).

Localities

At the type locality, the Birkhöhe Quarry, Zwiesel, Regen District, Lower Bavaria, Bavaria, Germany, zwieselite occurs in a granite pegmatite (Mindat).

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