In the upturned sedimentary beds which flank the Calico Hills, dipping
outward toward the desert plain on all sides of the uplift, except where
purely local disturbances have caused a reverse condition, are bedded
deposits of calcium borate and gypsum (calcium sulphate). Five miles
east of the town of Calico is the largest known deposit of calcium
borate in the district. The bed, or vein, as it is called, was
discovered some years since, and finally passed into the hands of the
present owners, the Pacific Coast Borax Company, whose extensive works
are located at Alameda, near San Francisco.