San Benito Mountain

San Benito Mountain is the highest mountain in the Diablo Range of California. The summit is at an elevation of 5,267 feet (1,605 m). The rock is composed of asbestos (chrysotile), an ultramafic rock. It weathers to produce serpentine soils with characteristically low levels of nutrients like nitrogen, phosphorus, potassium, and calcium, and high levels of magnesium and heavy metals including nickel and chromium. This means little vegetation grows in the area though there are some plants that only grow on such soils like the local endemic San Benito evening primrose. The Clear Creek Management Area includes the San Benito Mountain Research Natural Area, recognized for its unique pine and incense cedar forest assemblage. The Mediterranean climate is punctuated by cool, wet winters and hot, dry summers.

There are two superfund sites in the area, both associated with the mining and processing of chrysotile asbestos. There are also a handful of small mines producing gems and the minerals, but the Clear Creek Serpentine Area of Critical Environmental Concern was withdrawn from mineral entry on August 7, 2012.