Found in gemstone quality only in California, what mineral is named for the county in which it can be mined?

Benitoite can be found in Japan and Arkansas, but only San Benito County, California, does it have a special quality that makes it worthy of being called a "gemstone". There's a place in Coalinga which allows the general public to do their own digging and take home a quart-sized bag of the mineral.

Asked by Tom Cohen · Last updated 5 years ago · 9.2K views