picromerite
Mineralogy
noun
A mineral that is a sulphate of magnesium and potassium, K2Mg(SO4)2·6H2O, crystallizing in the monoclinic system and usually occurring as colourless or white masses and crusts.
Origin
Mid 19th century; earliest use found in Henry Watts (1815–1884), chemist. From picro- + ancient Greek μεριδ-, μερίς part, after Italian Picromeride.