glauconite
/ˈɡlɔːkənʌɪt
/noun [mass noun]
A greenish clay mineral of the illite group, found chiefly in marine sands.At the base of the Reading Formation are several metres of brown clay-rich sand with glauconite, flint pebbles and oyster shells....
- In addition, colors that can be produced by using mixtures of the just-mentioned basic pigments, in some cases along with glauconite and charred bone, are also noted and illustrated.
- Rounded 1 mm grains of glauconite occur in the Pentecost Sandstone.
Origin
Mid 19th century: from German Glaukonit, from Greek glaukon (neuter of glaukos 'bluish-green') + -ite1.