San Benito Mountain is the highest mountain in the

Diablo Range The Diablo Range is a mountain range in the California Coast Ranges subdivision of the Pacific Coast Ranges in northern California, United States. It stretches from the eastern San Francisco Bay area at its northern end to the Salinas Valley are ...

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...

. The summit is at an elevation of . The rock is composed of asbestos (chrysotile), an

ultramafic Ultramafic rocks (also referred to as ultrabasic rocks, although the terms are not wholly equivalent) are igneous and meta-igneous rocks with a very low silica content (less than 45%), generally >18% MgO, high FeO, low potassium, and are composed ...

rock. It weathers to produce serpentine soils with characteristically low levels of nutrients like

nitrogen Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...

phosphorus Phosphorus is a chemical element with the symbol P and atomic number 15. Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus, but because it is highly reactive, phosphorus is never found as a free element on Ear ...

potassium Potassium is the chemical element with the symbol K (from Neo-Latin ''kalium'') and atomic number19. Potassium is a silvery-white metal that is soft enough to be cut with a knife with little force. Potassium metal reacts rapidly with atmosph ...

, and

calcium Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar t ...

, and high levels of

magnesium Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic ta ...

and heavy metals including

nickel Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive but large pieces are slow ...

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.

Geology

The mountain, which rises to an elevation of , is the highest point in

San Benito County San Benito County (; ''San Benito'', Spanish for " St. Benedict"), officially the County of San Benito, is a county located in the Coast Range Mountains of the U.S. state of California. As of the 2020 census, the population was 64,209. The co ...

and the

. The mountain gets some snowfall during winter. The rock is a

chrysotile Chrysotile or white asbestos is the most commonly encountered form of asbestos, accounting for approximately 95% of the asbestos in the United StatesOccupational Safety and Health Administration, U.S. Department of Labor (2007)29 C.F.R.&nb ...

serpentine, a soft fibrous silicate material. Extreme shearing of the bedrock, combined with soil nutrient imbalances, has resulted in extensive areas of natural barrens completely devoid of vegetation. The serpentine soils harbor several rare plant species, including the Federally listed Threatened San Benito evening primrose (''Camissonia benitensis''). A unique pine and incense cedar forest occurs at the highest elevations of the mountain and in 1980, the San Benito Mountain Research Natural Area was designated an Instant Wilderness Study Area. The serpentine mass contains two superfund sites, Atlas Mine and Johns-Mansville. Both were associated with the mining and processing of chrysotile asbestos. Other minerals mined from the serpentine mass included cinnabar, chromite, magnesite, and jadeite. The Gem mine (private) located within the serpentine mass is the only source of gem-grade benitoite in the world. The rare minerals neptunite and joaquinite have also been found there.

Health and Safety Restrictions

The Clear Creek Management Area, which encompasses the San Benito Mountain Research Natural Area, was temporarily closed by the BLM from May 2008 to February 2014 due to concerns of visitor exposure to naturally occurring asbestos (chrysotile). The core area of the Clear Creek Management Area (approximately 35,000 acres) is the New Idria serpentine mass. The serpentine is highly sheared/pulverized and contains abundant chrysotile asbestos. Therefore, the U.S. Bureau of Land Management requires visitors to obtain permits to enter the Clear Creek Serpentine Area of Critical Environmental Concern. Recreational opportunities include hunting, camping, hobby gem/mineral collecting, mountain biking, horseback riding, hiking/backpacking, and sightseeing. Hobby gem and mineral collectors are drawn to the Clear Creek area, one of the most highly mineralized areas in California, by the presence of over 150 semi-precious minerals and gemstones. Among these are serpentine, jadeite, cinnabar, tremolite, topazite, neptunite, and the extremely rare California state gem, benitoite. There are two developed campgrounds in the CCMA, Oak Flat and Jade Mill, both with picnic tables, shade structures, fire rings, and pit toilet.

Permit and Season Information

Permit and Season Information for San Benito Mountain: *Serpentine Area of Critical Environmental Concern (ACEC) Permit: This free permit allows an individual to access the Serpentine ACEC within the Clear Creek Management Area for the duration of one day. Each person, regardless of age, entering the Serpentine ACEC is required to have a permit in their name and on their person. An individual is allowed a total of five permits per calendar year. *Vehicle Permit: Vehicles entering the Clear Creek Management Area, including the Condon Peak campground and trailhead, are required to have a Clear Creek Vehicle Permit. The permit is $5 per vehicle and allows the vehicle to enter the Clear Creek Management Area for seven days from the date of entry. Each vehicle must display the permit on its dash while in the Clear Creek Management Area. *Condon Peak Off-Highway Vehicle (OHV) Permit: Every ATV or Utility Terrain Vehicle (UTV) entering Condon Peak's trail network is required to have a permit. The permit cost is $10 and allows the ATV/UTV driver, age 16 and older, access to the route network at Condon Peak for seven days from the entry date.

References

External links

* {{cite gnis, 254202, San Benito Mountain Mountains of San Benito County, California Diablo Range Mountains of Northern California