Petrographic Thin-Section Laboratory at Solano

Can light pass through solid rock?! You bet! That is the nature of petrographic thin-section research.

At Solano, we were very fortunate to receive a donation of $65k worth of university-quality petrographic equipment from Chevron Research. This included a thin-section saw and microscope.

Over the past two years, we have completed the thin-section lab with a polisher/grinder and a digital camera. Solano is the only community college in Northern California with such equipment.

The first step in making a thin-section is to use a rough-cut saw to slice a rock sample to a thickness of one-half inch. One side of the sample is polished and mounted to a glass slide with epoxy. A cut-off saw is then used to slice the sample to about 1 millimeter (mm) thickness. A diamond grinder finally reduces the thickness to 0.03 mm – about 10 times thinner than a human hair.

Under the microscope, various polarizers and filters help identify minerals by their optical properties. The following two articles will highlight the use of petrographic thin-sections in geologic research.

-Article and Photos

by Mark Feighner

1A) Rock chip cut to about 1/2 inch thickness.

1B) Rock chip is polished and mounted to glass slide with epoxy.

2) Rock chip is trimmed and then ground with diamond wheel to about 30 microns thickness.