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Formula: KFeS2
Sulphide
Crystal system: Monoclinic
Specific gravity: 2.654 calculated
Hardness: 2
Streak: Brown-black
Colour: Deep purple
Environments
Hanswilkeite is a new mineral, approved in 2022.
Localities
At the type locality, Naẖal Gorer, Tamar Regional Council, Beersheba Subdistrict, Southern District, Israel,
hanswilkeite is a potassium-rich natural sulphide discovered in the pyrometamorphic suite of the
Hatrurim Formation. It occurs in sulphide-calcite assemblages confined to black-colored
calcite-spurrite
marbles. It forms single-crystal grains up to 1 mm in size,
isometric to lath-like, and often intergrown with less-common rasvumite.
Associated minerals include srebrodolskite,
tilleyite, fluormayenite,
cuspidine, fluorapatite,
oldhamite, pyrite and
andradite.
Hanswilkeite is the third discovered dithioferrate mineral: a sulfosalt that contains
[FeS2]− anion with iron in the Fe3+ state. Other known natural dithioferrates are
erdite and raguinite.
Hanswilkeite has a synthetic counterpart and a group of related synthetic sulphides and selenides, which
have been well studied. Hanswilkeite can be considered as an indicator of an extreme potassium-rich
environment superimposed onto anhydrous and oxidising formation conditions
(AM 110.6.956–965).
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