Buried within the ignimbrites and lavas, some orbs contain layers of biotite, bronzite, ilmenite and plagioclase around a centimetre-sized xenolith or orthopyroxene core.
12.
Primary ( magmatic ) mineral species also encountered in komatiites include olivine, the pyroxenes augite, pigeonite and bronzite, plagioclase, chromite, ilmenite and rarely pargasitic amphibole.
13.
Like enstatite, bronzite is a constituent of many mafic to ultramafic igneous rocks, such as, norite, gabbro, and especially peridotite, and of the serpentinites which have been derived from them.
14.
In the bronzite variety, ( Mg, Fe ) SiO 3, the iron ( II ) oxide ranges from about 12 to 30 %, and with still more iron there is a passage to hypersthene.
15.
Color is often gray, brown, or green, and the hardness is 5 6, and the specific gravity is 3.4 3.9 . On certain surfaces it displays a brilliant copper-red metallic sheen, or schiller, which has the same origin as the bronzy sheen of bronzite, but is even more pronounced.
