Where to Find Chalcedony in California

California chalcedony shows up in the desert agate districts and along the coast. The Mojave fields (Wiley's Well, Cady Mountains, Lavic) yield blue, white, and pink chalcedony in basalt and rhyolite. The San Diego County pegmatite belt produces chalcedony in association with tourmaline at the Himalaya and Stewart mines. Coast chalcedony turns up at Agate Beach in Marin County and Jade Cove in Monterey County as tide-tumbled pebbles. Smaller showings of dendritic and moss chalcedony occur in the Coso Range and the Argus Mountains. Field specimens clean up with a quick rinse in mild acid to remove desert caliche. The most productive ground is in Wiley's Well district (Riverside County), Himalaya mine area (San Diego County), Agate Beach (Marin County).

Casual hand collection of common rocks and minerals like chalcedony is allowed on most BLM and U.S. Forest Service land in California, with daily and annual limits set by the local field office. National parks, most state parks, and tribal land are off-limits. Always confirm rules before a trip.

Wiley's Well district (Riverside County) is the standout. Other strong ground includes Himalaya mine area (San Diego County), Agate Beach (Marin County).