San Benito Mountain, the highest peak in California’s Diablo Range at 5,267 feet, is defined by chrysotile serpentine geology that creates nutrient-poor, metal-rich soils, broad barrens, and specialized plant communities. Those harsh soils support rare species including the San Benito evening primrose, while higher elevations contain an unusual pine and incense cedar “sky island” forest within a protected research natural area. The mountain and surrounding Clear Creek region also have a long mining history tied to chrysotile asbestos and other minerals, including nearby gem-grade benitoite. Because of naturally occurring asbestos hazards, access to parts of the area is now controlled and permit-based.