"Although all mineral commodities mined in California are studied, special emphasis has been given construction aggregate because it is the state's most important mineral commodity in terms of tonnage, value, and societal infrastructure. As California's population continues to expand, the demand for minerals-especially building construction minerals such as aggregate-will similarly grow. Over 90% of these essential construction resources are transported by truck because unit trains and marine transport, although used, are currently uncommon in the state. Because such high-volume low-cost construction minerals are expensive to transport, and in order to minimize the environmental effects of trucking these resources from distant sources, it is beneficial-both economically and environmentally-that sand, gravel, and crushed stone resources be mined in reasonable proximity to growing communities."
Additional Mineral Resource Management information is available through the California Department of Conservation.