Hendricksite

hendricksite

hancockite

axinite

bustamite

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Formula: KZn₃(Si₃Al)O₁₀(OH)₂
Phyllosilicate (sheet silicate), mica group
Specific gravity: 2.86 to 3.43
Hardness: 2½ to 3
Streak: Red-brown
Colour: Coppery brown, bronze-brown, dark reddish brown to reddish black
Common impurities: Ti,Fe,Ca,Ba,Li,Na,F
Environments

Metamorphic environments

Hendricksite is the only zinc-dominant mica group member currently known (2019) (Mindat)

Localities

There are two co-type localities, both at the Franklin Mine, Sussex county, New Jersey, USA. Here franklinite is restricted to lens or sheet like skarn bodies in a metamorphosed stratiform zinc deposit (HOM, Mindat), associated with andradite, rhodonite, bustamite, calcite, barium feldspars, franklinite, willemite, axinite, vesuvianite, hardystonite, cummingtonite and hancockite, and also members of the diopside - hedenbergite - johannsenite series (HOM, Mindat, AM 51.1107-1123).

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