The story
From Joseph W. Greig, American mineralogist, + -ite.
Etymology from Wiktionary, CC BY-SA 4.0.
greigite
Today it means: 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. Full definition →