Clinopyroxene

Optical Properties:

The clinopyroxene group includes diopside, augite, jadeite, pigeonite, hedenbergite, and others. It is generally difficult to distinguish between individuals in this group optically. All are biaxially positive, with moderate relief and up to second order birefringence colors, and all have pyroxene 87 degree cleavage and inclined extinction. Many clinopyroxenes have pale greenish pleochroism.

The photos above show a clinopyroxene grain in crossed (left) and uncrossed polarizers; exsolution lamellae of orthopyroxene are clearly visible in the left photo.

Clinopyroxenes are abundant in many intrusive and extrusive igneous rocks, including diorite, gabbro, the peridotite family, basalt, and andesite. They also occur in metamorphosed mafic rocks, and jadeite is a constituent of some blueschist facies rocks.


Above: clinopyroxene crystal in basalt: crossed polarizers on left, plane light on right. Field of view 1.5 mm.

Complex twins in lunar mare clinopyroxene in crossed polarizers (left). Two cleavages in pyroxene in plane polarized light (right).