About this location
Amboy Crater, a roughly 79,000-year-old basaltic cinder cone in San Bernardino County, is one of the most-visited sites in Mojave Trails National Monument and a National Natural Landmark. Rockhounding has reportedly been a family activity across the broader Mojave Trails area for more than a century, and casual collecting is currently allowed under BLM's standard rules while the monument's management plan is finalized — though a 2023 news report flagged a proposed rule that could restrict rock-hunting here, so this is worth rechecking before a trip. The specimen list attached to this location is a mixed bag: some of it fits the crater itself, some of it belongs to a different site several miles away.
Always seek permission where required, follow local laws, and practice Leave No Trace. Locations and details are community-submitted and may be inaccurate. Not sure what's legal here? Read our full guide to rockhounding laws by land type.
Found Here
Jasper — plausible given the volcanic terrain and the nearby Marble Mountain Fossil Bed/Cady Mountains area, both cited as popular Mojave Trails rockhounding grounds. Obsidian — not independently confirmed for this specific basaltic cinder cone; Amboy's lava flows are basalt, a rock type that doesn't typically produce obsidian (a silica-rich volcanic glass), so this specimen may be a mislabel worth Board review. Boltwoodite — a genuine, rare fluorescent uranium mineral documented in the area, but specifically at the New Method Mine (formerly the Hope Uranium prospect), about 6.6 miles northeast of Amboy town — not confirmed to occur at the crater itself.
Difficulty
Getting there
The BLM-marked Western Cone Trail from the day-use parking area is the standard route to the crater rim; the site sits along old Route 66 near the town of Amboy.
Collecting here
Surface picking under general BLM casual-use rules. Bring sun protection and water, and watch for both rattlesnakes and old military ordnance — both specifically flagged by BLM for this stretch of desert.
Know before you go
BLM's Needles Field Office (760-326-7000) is the contact for current rockhounding rules — call ahead, since Mojave Trails National Monument's management plan has been under development and at least one 2023 report flagged a proposed rule that could restrict rock-hunting in the monument. Dispersed camping is not allowed in the main Amboy Crater parking lot, though it's permitted elsewhere on monument BLM land.
Location on Map
Coordinates: 34.54478, -115.79235
Nearby rockhounding locations
- Bristol Dry Lake — Celestite ConcretionCA · 8.8 mi
- UCLA loc. 3226 — FossilCA · 16.1 mi
- Carlyle — Bismuth, CopperCA · 32.7 mi
- Virginia Dale — Gold, IronCA · 33.3 mi
- Top Nest — Azurite, ChrysocollaCA · 33.3 mi
- Bell Gilroy — Copper, GalenaCA · 32.8 mi
Frequently asked questions
Can you collect rocks at Amboy Crater?
Casual rockhounding is currently allowed under BLM's standard rules for Mojave Trails National Monument, but call the BLM Needles Field Office to confirm current policy before a trip, since a 2023 report noted a proposed rule that could restrict collecting in the monument.
Is boltwoodite found at Amboy Crater itself?
Not confirmed — the documented boltwoodite locality (New Method Mine) sits about 6.6 miles northeast of Amboy town, not at the crater.
What's the best-documented Amboy-area rockhounding ground?
The Cady Mountains and Marble Mountain Fossil Bed near Amboy are cited by regional sources as popular spots for chalcedony, calcite, copper ores, and lace agate.
Who manages Amboy Crater?
The BLM's Needles Field Office, within Mojave Trails National Monument.
⚠️ Always verify current regulations, weather conditions, and access requirements before visiting any location. Information provided is based on community submissions and may not be current or accurate.
Sources
- https://en.wikipedia.org/wiki/Amboy_Crater — geology, trail description, BLM contact info.
- https://www.blm.gov/visit/amboy-crater — official BLM visitor page, land manager and safety notes.
- https://www.route66news.com/2023/07/25/proposed-rule-may-ban-rock-hunting-in-mojave-trails-national-monument/ (via search) — proposed regulatory change flag.
- https://blackvoicenews.com/2018/06/09/rockhounding-in-mojave-trails-national-monument/ (via search) — Cady Mountains/Marble Mountain regional collecting context.
- https://www.mindat.org/min-716.html and New Method Mine locality data (via search) — boltwoodite location specifics, 6.6 miles NE of Amboy.
Recommended Gear for California
Estwing E3-22P Rock Pick
The industry-standard 22oz geological hammer. One-piece forged steel with shock-reduction grip.
Clear Anti-Fog Safety Glasses (4 Pack)
Adjustable, anti-fog lenses for clear vision in any conditions. About $5 per pair.
Watertight Medical Kit
Compact, waterproof first aid kit with bandages, moleskin, and field essentials.
Southwest Treasure Hunter's Gem and Mineral Guide
Whether you're digging for the first time or are an experienced rockhound or "prospector," with a simple rock hammer and...
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