Jeankempite

jeankempite

algodonite

domeykite

rauenthalite

Images

Formula: Ca5(AsO4)2(AsO3OH)2(H2O)7
Arsenate
Specific gravity: 2.92
Hardness: 1½
Streak: White
Colour: Colourless to white
Luminescence: No fluorescence under long or short wave UV
Common impurities: Mg,Na,S
Environments


Hydrothermal environments

Jeankempite is a relatively new mineral, approved in 2018 and to date (May 2022) reported only from the type locality.

Localities

At the type locality, the Mohawk mine, Mohawk, Keweenaw county, Michigan, USA, jeankempite was discovered amongst coatings of arsenate minerals on oxidised copper arsenides. It occurs as lamellar bundles of colourless to white plates up to 1 mm wide and is visually indistinguishable from guérinite, with which it forms intergrowths. It is suggested that jeankempite formed due to dehydration of preexisting guérinite. Jeankempite occurs as tabular crystals, intergrown with guérinite, and as a secondary phase on "mohawkite" (a mixture of algodonite, copper, domeykite and paxite) and calcite. Associated minerals include algodonite, annabergite, calcite, copper, dolomite, domeykite, guérinite, lavendulan and rauenthalite (MM 84.959-969, Mindat).

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