margarite

[mahr-guh-rahyt] /ˈmɑr gəˌraɪt/
noun
1.
Mineralogy.
  1. a gray, pink, or yellow mica, occurring in brittle monoclinic crystals.
  2. an aggregate of small, rudimentary crystals resembling minute globules in a row: found in glassy volcanic rocks.
2.
Obsolete. a pearl.
Origin
before 1000; Middle English, Old English: pearl < Latin margarīta < Greek margarī́tēs, perhaps < Iranian (compare Pahlavi marvārīt pearl), with final element conformed to Greek -ītēs -ite1
British Dictionary definitions for margarite

margarite

/ˈmɑːɡəˌraɪt/
noun
1.
a pink pearly micaceous mineral consisting of hydrated calcium aluminium silicate. Formula: CaAl4Si2O10(OH)2
2.
an aggregate of minute beadlike masses occurring in some glassy igneous rocks
Word Origin
C19: via German from Greek margaron pearl
Word Origin and History for margarite
n.

"a pearl," late Old English, from Late Latin margarita (see Margaret). Figuratively, "that which is precious or excellent, a priceless quality or attribute;" also used as an epithet for Christ, Mary, etc., late 13c. Also margerie (mid-14c.).