GLAUCONITE
glauconite
(noun) a green mineral consisting of hydrated silicate of potassium or iron or magnesium or aluminum; found in greensand
Source: WordNet® 3.1
Noun
glauconite (plural glauconites)
(mineral) A greenish form of mica found in greensand
Source: Wiktionary
Glau"co*nite, n. Etym: [Cf. F. glauconite, glauconie, fr. L. glaucus.
See Glaucous.] (Min.)
Definition: The green mineral characteristic of the greensand of the chalk
and other formations. It is a hydrous silicate of iron and potash.
See Greensand.
Source: Webster’s Unabridged Dictionary 1913 Edition