The Contact: Cross Polarized Gabbro

This is one in a series of over 30 quilts that I call The Contact. I am pursuing the Sierra Nevada of California, from the geologic formations formed eons ago to the crystals you can see under a microscope.
Gabbro is a dark intrusive rock that is sometimes associated with gold-bearing quartz veins. It is monotonous and plain to the naked eye, but polarized light passing through a 30-micron thin section reveals an infinite variety of sharply contrasting crystal twins of feldspar intergrown with colorful pyroxene.