Grischunite

grischunite

sarkinite

brandtite

berzeliite

Images

Formula: NaCa₂Mn²⁺₅Fe³⁺(AsO₄)₆.2H₂O
Hydrated normal arsenate, wicksite group, manganese-bearing mineral
Crystal System: Orthorhombic
Specific gravity: 3.8 measured, 4.144 calculated
Hardness: 5
Streak: Brown
Colour: Dark red-brown
Environments

Metamorphic environments

Grischunite is a rare arsenate found only at its type locality to date (March 2022).

Localities

At the type locality, Falotta, Tinizong, Oberhalbstein, Albula Valley, Grisons, Switzerland, grischunite occurs as an alteration product of sarkinite, with which it is intimately intergrown, in a manganese deposit. Associated minerals include sarkinite, brandtite, manganoan berzeliite, tilasite, rhodochrosite and braunite (AM 71: 227-228).

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