Portal:Minerals/Did you know/3

... that the Lewisian gneiss (pictured), forms the basement to Torridonian and Cambro-Ordovician sedimentary rocks in the Hebridean Terrane?
... that abernathyite is both fluorescent and radioactive and is named for the mine operator who discovered it?
... that the minerals armalcolite, pyroxferroite and tranquillityite were discovered in lunar rocks?
...that the streak of a mineral, the color of the mark it makes when rubbed on a plate, is usually a more consistent identifier than the color of the original mineral?