plenargyrite
/plɪˈnɑːdʒɪrʌɪt/Mineralogy rare
noun
A mineral consisting of a sulphide of silver and bismuth, AgBiS2, that is a paramorph of matildite.
Origin
Late 19th century; earliest use found in The Century Dictionary. From German Plenargyrit, apparently from classical Latin plēnus full + ancient Greek ἄργυρος silver + German -it, after Miargyrit.