chloritoid

noun

chlo·​ri·​toid

-rəˌtȯid

plural -s

: a mineral (Mg₁Fe)AlSiAlO₅(OH)₂ consisting of a silicate of aluminum and ferrous iron with magnesium occurring usually in dull green to gray or grayish black masses of brittle folia and related to the brittle micas (as clintonite)

Word History

Etymology

German, from chlorit chlorite (mineral) + -oid

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