Metachert breccia

Metachert breccia

Metachert

Green metachert breccia. with quartz-filled fractures. Metachert rock like this is common in the lower Franciscan Formation (Jurassic) in the central Coastal California region. This sample is a stream cobble from Tres Pinos Creek area, San Benito County, California.
https://gotbooks.miracosta.edu/rocks/metamorphic/24.html 2/2/2021