greigite

== English == === Etymology === From Joseph W. Greig, American mineralogist, +‎ -ite. === Noun === greigite (uncountable) (mineralogy) A magnetic form of iron sulfide, Fe2+Fe3+2S4, analogous to magnetite, produced by microorganisms and found in lake sediments; Note: half the iron ions are ferrous and half ferric. === Further reading === David Barthelmy (1997–2026), “Greigite”, in Webmineral Mineralogy Database. “greigite”, in Mindat.org, Keswick, Va.: Hudson Institute of Mineralogy, 2000–2026. OED 2006