glaucophane

noun

glau·​co·​phane

ˈglȯkəˌfān

plural -s

: a mineral Na₂(Mg,Fe)₃Al₂Si₈O₂₂(OH)₂ consisting of a blue, bluish black, or grayish silicate of sodium, aluminum, iron, and magnesium occurring in certain crystalline schists

Word History

Etymology

German glaukophan, from glauk- glauc- + -phan -phane

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