Mineral/rock

Derived from or for

Ochre

Latin and Greek ochra = pale or pale yellow alluding to its color

Offertite (zeolite)

Albert Jules Joseph Offret (1857-?), professor, Lyons, France

Olivine

Latin oliva = olive alluding to its olive green color

Onyx

Greek onyx = claw, fingernail, hoof in reference to the color

Opal

from Sanskrit upala = stone or precious stone

Orthoclase

Greek for straight and klasis = fracture in reference to its cleavage angle of 90°