Grain with 1 gray interference colors will give optic axis figure with many isochromes or color rings that is characteristic of olivine. Some of the larger grains of olivine may look twinned, due to sweeping extinction in which domains bounded by straight, boundaries are out of parallel by 1 or 2 . Compare this texture with the strained sample from Lherz and the annealed sample from Day Brook. Enstatite is distinguished from diopside by their optic axis figures. While diopside has interference colors up to 2 blue, enstatite rarely exceeds 1 gray.
Spinel occurs in irregular grains that appear to fit in among the olivines.
It has high relief and is deep olive brown in plane light. It is isotropic under crossed polars. These aggregates are interpreted as crystallized partial melt, approximating alkali basalt in composition, that formed in the mantle, possibly prior to inclusion in the basalt magma. Most of what you see is isotropic glass formed by quenching melt, and holes or vesicles . Plagioclase occurs as tiny, needle-like microlites .