Crystal Springs Reservoir: Chromite Rockhounding in San Mateo County, California

Updated July 2026

Crystal Springs Reservoir is a mapped rockhounding spot in San Mateo County, California. Reported finds include chromite. Below: coordinates, access notes, nearby spots, and trip-planning links.

Quick details

Access: Permission required
County: San Mateo County
State: California
Nearest road: Sawyer Camp Trail
Postcode: 94030
Coordinates: 37.54739, -122.38739

Geology at Crystal Springs Reservoir

This spot sits on ground mapped as Franciscan Complex, Greenstone that formed roughly 200 to 66 million years ago. Metamorphic rock like this weathers into resistant float, and minerals that survive transport typically concentrate in nearby drainages.

Mapped unit: Franciscan Complex, Greenstone
Age: 200–66 Ma (Jurassic to Cretaceous)
Elevation: 450 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 Crystal Springs Reservoir

Conditions here are workable year-round, with typical highs from 56°F in winter to 71°F in summer.

Climate normals: NOAA 1991-2020 monthlies, SAN FRANCISCO INTL AP station (5 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: April 1, 2026

BLM California — Recreational mineral collecting
California Geological Survey
CDFW — Suction Dredge Mining Permit Program
Community submissions reviewed against published agency rules

Found at Crystal Springs Reservoir

Each chip opens all spots that produce that material; the encyclopedia link opens the full ID and field guide.

Chromite Encyclopedia →

Nearby rockhounding spots

Other rockhounding spots within driving distance of Crystal Springs Reservoir.

Crystal Springs Reservoir FAQ

Where is Crystal Springs Reservoir?+

Crystal Springs Reservoir is in San Mateo County, California, at 37.54739, -122.38739. Nearest road: Sawyer Camp Trail.

What rocks and minerals can you find at Crystal Springs Reservoir?+

Crystal Springs Reservoir is reported to produce Chromite.

Is collecting allowed at Crystal Springs Reservoir?+

Permission required before collecting. Requires landowner or agency permission before any collecting. Do not enter without explicit authorization. Always confirm current rules with the managing agency before a trip.

What tools should I bring to Crystal Springs Reservoir?+

A rock hammer, sturdy gloves, safety glasses, and a collecting bag cover the basics here. Add a spray bottle: wet rock shows color and pattern that dry rock hides.

When is the best time to visit Crystal Springs Reservoir?+

Crystal Springs Reservoir is workable year-round.

How do I get to Crystal Springs Reservoir?+

Open the directions link to navigate to 37.54739, -122.38739 in Google Maps. The nearest road is Sawyer Camp Trail.

More rockhounding in California

See all 97 California spots →

Open Crystal Springs Reservoir on the map

Use the RockHoundR app for live land overlays, weather, geology, directions, and saved finds.