margarosanite
noun
mar·ga·ro·san·ite
ˌmärgəˈrōsᵊnˌīt
plural -s
: a mineral PbCa2(SiO3)3 consisting of a lead calcium silicate occurring in colorless lamellar masses
Word History
Etymology
Greek margaron pearl + sanis board + English -ite; from its pearly luster and lamellar structure; probably akin to Greek sathē penis, sainein to wag the tail, Old English thūma thumb