San Simeon Beaches: Moonstone Rockhounding in San Luis Obispo County, California

Quick details

Access

Public area

County

San Luis Obispo County

State

California

Nearest road

Cabrillo Highway

Postcode

93452

Coordinates

35.64214, -121.18331

Geology at San Simeon Beaches

This spot sits on alluvium and marine deposits, mapped as coarse alluvium that formed within roughly the last 5 million years. Loose deposits like these are float-collecting ground: erosion keeps moving durable rocks and minerals into gravel bars, cutbanks, and washes.

Mapped unit

alluvium and marine deposits

Age

5 Ma to present (Pliocene to Holocene)

Rock types

coarse alluvium

Elevation

20 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 San Simeon Beaches

Conditions here are workable year-round, with typical highs from 65°F in winter to 80°F in summer.

Climate normals: NOAA 1991-2020 monthlies, HEARST CASTLE station (3 mi away), adjusted for elevation.

Land & collecting status

Generally open to casual rockhounding

Most public-tagged spots sit on BLM, U.S. Forest Service, or other federal land where reasonable hand collecting of common rocks and minerals is allowed. Confirm posted rules and active mining claims before you dig.

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 San Simeon Beaches

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

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