Amboy Crater: Boltwoodite & Jasper Rockhounding in San Bernardino County, California
Updated June 2026
Amboy Crater is a mapped rockhounding spot in San Bernardino County, California. Reported finds include boltwoodite, jasper, obsidian. Below: coordinates, access notes, nearby spots, and trip-planning links.
Map showing Amboy Crater in San Bernardino County, California
Quick details
- Access
- Permission required
- County
- San Bernardino County
- State
- California
- Nearest road
- Amboy Crater Trail
- Postcode
- 92304
- Coordinates
- 34.54478, -115.79235
Geology at Amboy Crater
This spot sits on Recent (Holocene) volcanic flow units, unit 4 (Mojave Desert), mapped as basalt and basanite that formed within roughly the last 3 million years. Volcanic ground like this is where agate, jasper, and other chalcedony typically form, filling old gas pockets and fracture seams in the flow rock.
- Mapped unit
- Recent (Holocene) volcanic flow units, unit 4 (Mojave Desert)
- Age
- 3 Ma to present (Pleistocene to Holocene)
- Rock types
- basalt and basanite
- Elevation
- 820 ft
Geologic mapping via Macrostrat and the underlying state geological survey maps (CC BY 4.0). Bedrock at the surface can vary within a mapped unit.
Best time to visit Amboy Crater
Best months: October to May. Typical highs run 105°F in midsummer and 66°F in midwinter, with winter lows near 53°F. Summer heat here is intense, so carry more water than you think you need and work the early morning.
Climate normals: NOAA 1991-2020 monthlies, MITCHELL CAVERNS station (31 mi away), adjusted for elevation.
Land & collecting status
Permission required before collecting
Requires landowner or agency permission before any collecting. Do not enter without explicit authorization.
Public-land rules vary by agency, season, and field office. The RockHoundR app pulls live BLM, USFS, NPS, and tribal overlays so you can see exactly which agency manages the ground at this spot.
Sources & verification
Spot details combine the public RockHoundR location dataset, normalized mineral labels, agency land-status checks in the app, and community submissions. Coordinates are approximate until verified in the field.
State guidance last verified:
- BLM California — Recreational mineral collecting
- California Geological Survey
- CDFW — Suction Dredge Mining Permit Program
- Community submissions reviewed against published agency rules
Found at Amboy Crater
Each chip opens all spots that produce that material; the encyclopedia link opens the full ID and field guide.
Nearby rockhounding spots
Other rockhounding spots within driving distance of Amboy Crater.
- Bristol Dry LakeSan Bernardino County, California · 9 mi awayCelestite Concretions
- Afton CanyonTop pick in CaliforniaSan Bernardino County, California · 48 mi awayOpalite, Jasper
- Midway Area (Lavic Jasper)San Bernardino County, California · 51 mi awayLavic Jasper
- Rouse HillRiverside County, California · 82 mi awayAmazonite, Idocrase, Rose Quartz
- Unnamed Location (Fire Agate)Top pick in CaliforniaRiverside County, California · 91 mi awayChalcedony, Fire Agate
- Eagle CragsSan Bernardino County, California · 93 mi awayBlue Agate, Bentonite, Calcite
- Old Quarry (Riverside)Riverside County, California · 100 mi awayAxinite
- Area Near Jenson QuarryRiverside County, California · 100 mi awayHornblende
Across the state line from Amboy Crater
Amboy Crater is close enough to the California border that the next-closest rockhounding spots are in a neighboring state. Worth knowing if you are already on the road.
Amboy Crater FAQ
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More rockhounding in California
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