Yours, Etc.: Origins and Uses of 8 Sign-Offs
precious stone, 1560s, replacement from Middle French of Middle English turkeis, turtogis (late 14c.), from Old French fem. adjective turqueise "Turkish," in pierre turqueise "Turkish stone," so called because it was first brought to Europe from Turkestan or some other Turkish dominion (Sinai peninsula, according to one theory). Cognate with Spanish turquesa, Medieval Latin (lapis) turchesius, Middle Dutch turcoys, German türkis, Swedish turkos. As a color name, attested from 1853.
A blue to bluish-green or yellowish-green triclinic mineral that occurs in reniform (kidney-shaped) masses with surfaces shaped like a bunch of grapes, especially in aluminum-rich igneous rocks such as trachyte. In its polished blue form it is prized as a gem. Chemical formula: CuAl6(PO4)4(OH)8·5H2O