The light colored background is a single crystal of diopside, a calcium- rich pyroxene. The pools of brightly colored crystals are individual plagioclase grains. The plagioclase grows through the pyroxene in a grid pattern that resembles a wire screen or a sieve. This pattern is controlled by cleavage planes in the pyroxene. Look for tiny bubbles inside some of the plagioclase grains. These are places where fluid is trapped inside the growing crystals.

Crossed polarizers with gypsum plate