Oceanview Mine, located in northern San Diego county, is a pegmatite mine producing tourmaline, kunzite, triphane, morganite, aquamarine, quartz, cleavelandite, and lepidolite. You can bring your kids to mine for a fee: Dig for Gems!
Jeff Swanger owns the mine, and dreamt of finding gems since he was a boy growing up nearby. Find out more about him and his fellow miners here.
According to Geology.com: "Pegmatites are extreme igneous rocks that form during the final stage of a magma's crystallization. They are extreme because they contain exceptionally large crystals and they sometimes contain minerals that are rarely found in other types of rocks."