Layers
Rock Types
Explore Adventures
Pick a region and plan your rockhounding trip. We'll show you every gem site, the geology, what to bring, and a suggested route.
Roadside Rockhounding
Pull over, grab your hammer, and start finding gems. These spots are right off the highway — no hike required. Sean approved.
Gem Hunting Sites
Historic & Active Mines
From working fee-dig operations to atmospheric abandoned shafts — explore America's mining heritage and find out what you can still dig up today.
Mining Ghost Towns
Boom and bust wrote the story of the American West. These abandoned mining towns are frozen in time — and many still have minerals scattered on the ground.
Geology Guide
What to Look For
North America sits on some of the most geologically diverse terrain on Earth. Ancient plate collisions, volcanic eruptions, and millions of years of metamorphism have created ideal conditions for gem and mineral formation across the continent.
Tip: Click any colored geology overlay on the map to explore vein systems, formation history, and undiscovered potential for that region.
Rock Types & What They Yield
Volcanic (Rhyolite & Basalt)
Gems: Fire opal, agate, jasper, obsidian, thundereggs
Rhyolitic flows create gas pockets (vesicles) that fill with silica-rich fluids over millennia, forming agates and opals. Look for light-colored, banded outcrops with visible cavities.
Metamorphic (Schist & Gneiss)
Gems: Garnet, tourmaline, beryl, kyanite
High heat and pressure transform minerals into gem-quality crystals. Pegmatite dikes intruding into schist are prime targets — San Diego County's famous tourmaline mines sit in exactly this geology.
Sedimentary (Limestone & Shale)
Gems: Geodes (quartz/calcite), fossils, septarian nodules
Ancient seabeds deposited layers that trap mineral-rich water. Geodes form as hollow cavities fill with crystals over millions of years. Hauser Geode Beds are a prime example.
Plutonic / Granitic
Gems: Tourmaline, aquamarine, morganite, kunzite, quartz crystals
Slow-cooling magma chambers allow large crystals to grow, especially in pegmatite pockets. The gem pegmatites of Riverside and San Diego counties are world-famous.
Alluvial / Desert Pavement
Gems: Chalcedony roses, agate, jasper, petrified wood
Erosion concentrates durable gemstones on desert surfaces. Simply walking washes and deflation surfaces after rain can yield excellent specimens. Lavic Siding is a classic spot.
Tips for Buying Land
- BLM vs. Private: Many gem sites are on Bureau of Land Management land (free to collect for personal use). Private parcels adjacent to known sites may be available.
- Water rights: In California, check if the parcel includes riparian rights for fishing/camping.
- Mining claims: Unpatented mining claims on BLM land can be purchased — check the BLM LR2000 database.
- County auctions: San Bernardino and Kern counties regularly auction tax-defaulted desert parcels, often for under $5,000.
- Zoning: Verify the parcel allows recreational/camping use. Many desert parcels are zoned RL (Rural Living).
Essential Gear
- Rock hammer (flat + pick end), chisels, pry bars
- Safety glasses and gloves
- Buckets and bags for specimens
- UV flashlight (fluorescent minerals glow!)
- GPS / offline maps (cell service is sparse)
- Plenty of water — 1 gallon per person per day minimum in the desert