Wallkilldellite

minerals

franklinite

willemite

adamite

Formula: Ca2Mn2+3(AsO4)2(OH)4.9H2O
Hydrated arsenate with hydroxyl
Specific gravity: 2.90
Hardness: 3
Streak: Pale orange
Colour: Dark red to nearly black
Environments

Metamorphic environments

Wallkilldellite is an extremely rare arsenate.

Localities

The type locality is the Sterling mine, Sterling Hill, Ogdensburg, Franklin Mining District, Sussex county, New Jersey, USA. Here wallkilldellite is found only rarely in massive granular franklinite - willemite ore from a metamorphosed stratiform zinc orebody, associated with manganoan cuprian adamite, franklinite, willemite and calcite (HOM).

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