miargyrite
/mʌɪˈɑːdʒɪrʌɪt/Mineralogy
noun
A monoclinic sulphide of silver and antimony, AgSbS2, a minor ore of silver which usually occurs as thick, tabular, steel-grey to black crystals, and contains less silver than the related minerals proustite and pyrargyrite.
Origin
Mid 19th century; earliest use found in Thomas Thomson. From German Miargyrit from mi- (from ancient Greek μείων less: see meio-) + ancient Greek ἄργυρος silver + -it, so named because the mineral contains less silver than prousite.