Mineral Resources Program

Since 1880, the California Geological Survey (CGS) has studied, documented, and mapped the state's mineral resources and, more recently, mineral hazards. Both are very important to Californians for different reasons; mineral resources are the backbone of the state's infrastructure, and identifying mineral hazards helps mitigate risks to the health and safety of Californians. Scroll through to learn how CGS' Mineral Resources Program is key to the Department of Conservation's commitment to California.

A mineral resource is a naturally occurring mineral deposit with a feasible way to be economically extracted. The Mineral Resources Program currently focuses on industrial materials, construction materials, and metallic and rare minerals. Let's explore the importance of mineral resources in our daily lives.

The primary goal of mapping California's mineral resource potential is to ensure that important mineral resources do not become inaccessible due to uninformed land-use decisions. Knowing where different mineral resources are located helps inform local and statewide land-use decisions. The Mineral Resources Program performs objective mineral land classification (MLC), based exclusively on geology and without regard to existing land use or ownership, to assist in the protection and wise development of California's mineral resources.

Minerals surround us in our everyday lives, from the cars we drive to work, to the stoves we use for cooking. Some of these minerals are largely imported from other countries, meaning that a disruption of that supply chain would have significant consequences for the economy and/or national security of the United States. These minerals are called "critical minerals." Under Executive Order 13817, The United States Geological Survey (USGS) drafted a list of 35 critical minerals in 2018⁵ ⁶. California has a diverse assemblage of rock types and geologic settings making it favorable for many types of minerals and metals. 34 of the 35 critical minerals have been discovered within the state, and many have been mined and produced, including tungsten, rare earth elements (REE), chromite, lithium, platinum, potash, strontium, and tin.

Mineral resources benefit people in California in many ways. However, mineral hazards can negatively impact public health and safety and the environment. Since the 1970's, the CGS has investigated different types of mineral hazards including naturally-occurring asbestos (NOA), radon, and various heavy metals -- like mercury and arsenic-- associated with past mining activities.

The flexible, high tensile-strength fibers that comprise asbestos are actually a naturally occurring crystal form of some minerals. While asbestos has important industrial uses, such as making fireproof materials, it can also cause lung diseases, including cancer, if inhaled. 

In California, these “asbestiform” minerals occur naturally in rocks found throughout the state, most commonly in serpentinite. Serpentinite is a metamorphic rock composed of magnesium and silica. When these minerals are disturbed through construction, or exposed to weathering at the ground surface, they may produce airborne asbestos particles that pose an inhalation hazard to people.  

The Mineral Resources Program produces maps showing the relative likelihood for the presence of NOA. These maps are produced by compiling and interpreting detailed data on geologic materials, soils, and known asbestos occurrences. These maps can be used to help individuals and community planners select and engineer building sites to minimize human exposure to NOA. They can also be used to help ensure that proper asbestos safety measures, such as dust control, are taken during public and private construction projects.

Radon, the 86th element in the periodic table, is a radioactive gas that causes lung cancer. You can’t see radon, and you can’t smell it or taste it. But it may be a problem in your home. Radon comes from the natural (radioactive) breakdown of uranium and thorium in soil, rock, and water and gets into the air you breathe.  

It can get into any type of building—homes, offices, and schools—and result in a high indoor radon level. You are most likely to get your greatest exposure at home, where you spend most of your time. Radon has been found in every county in California, but the presence of radon is much more likely in some areas than others due to the underlying geology. Every Californian is encouraged to test their home. Information about radon testing can be found below.

The U.S. Environmental Protection Agency (EPA) estimates that 1 in 15 houses have elevated radon levels, and that radon is responsible for approximately 20,000 lung cancer deaths in the US annually.

In California, radon may be particularly elevated in organic-rich black marine shales, and certain igneous rocks. Increased amounts of radon will be generated in the subsurface at these locations. Because radon is a gas, it moves easily through the soil and can find its way into a buildings indoor air through cracked slabs or basement walls.

While these rock types are widespread in California, their presence alone does not mean that radon will be produced in elevated concentrations. Local geochemical conditions and geologic structures within these rocks can combine to produce elevated radon in specific areas throughout a region.  

The Mineral Resources Program collaborates with the California Department of Public Health (CDPH) to generate detailed radon potential maps. These maps build upon the work of the U.S. EPA and CDPH to incorporate geology, indoor radon concentrations, and evaluations of rock and soil uranium to help identify in greater detail where elevated radon hazards may be present.

To learn more about radon occurrences in California, testing, and remediation, explore the websites of the  CGS Mineral Resources Program-Indoor Radon  page,  California Department of Public Health , and  U.S. EPA . 

The examples above are just some of the ways that the Mineral Resources Program supports The Department of Conservation’s commitment to carbon and watershed management, a sustainable economy, and provides public health protection for California’s people.  For more information, please visit  Department of Conservation  and  CGS Mineral Resources Program  sites.

We invite you to share questions and comments at our  CGS website .

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