Rockhounding San Luis Obispo County: The Club List and the Rules on Each Site

San Luis Obispo County has a lot of collectable rock for its size. Agate and jasper wash up on the beaches, Cuesta Ridge has quartz crystals and geodes, Shell Creek has Miocene shell beds, and Nipomo Mesa is known for its own agate. The trouble is that almost every site sits on land with different rules: a state beach, a national forest, a national monument, a wildlife area, or a private farm.

The SLO Gem & Mineral Club keeps a list of county collecting areas, and its map comes with a caution worth reading before anything else: “Check land status before you go. National monuments and most state parks do not allow collecting. Private land and mining claims are off-limits without permission. Historic mercury mines are hazardous.” The map also says its pins mark general areas, not exact collecting spots.

Below, the club’s sites are grouped by who manages the land, with what each agency’s own rules say. On any single parcel, the district or field office has the final word.

The rules, agency by agency

California State Parks: no collecting unless the unit allows it

The default rule for state park units is 14 CCR § 4307: “No person shall destroy, disturb, mutilate, or remove earth, sand, gravel, oil, minerals, rocks, paleontological features, or features of caves.” The same section adds that rockhounding “may be permitted” as defined in § 4301(v), which covers “the recreational gathering of stones and minerals found occurring naturally on the undisturbed surface of the land.”

So a state park or state beach is closed to collecting unless that unit says otherwise. Fossils are never covered by the rockhounding exception. Ask the unit before you pick up agate on a state beach.

Los Padres National Forest: open for hobby collecting, with limits

The Forest Service’s national Rockhounding Guide (FS-1091, June 2017) says “Most national forest lands are open for rock and mineral collecting” for personal, noncommercial use. The conditions:

• No mechanical equipment.
• No conflict with existing mining claims, leases or permits.
• “Only remove small reasonable amounts of material for personal use.”
• In national monuments, wilderness and other protected areas, “collecting may or may not be allowed.”

Artifacts can never be collected on national forest land (36 CFR 261.9(h)). Only common invertebrate and plant fossils can be casually collected, and petrified wood falls under a separate limited free-use rule (36 CFR 228.62).

You will sometimes see a figure of about 10 pounds a day quoted for casual collecting on Forest Service land. Neither the national guide nor 36 CFR 228 gives a poundage. They say “small reasonable amounts.” I couldn’t find a Los Padres page on rockhounding, so for Cuesta Ridge, call the Santa Lucia Ranger District.

BLM and Carrizo Plain National Monument: ask first at Soda Lake

On BLM land, 43 CFR 8365.1-5(b) allows reasonable noncommercial amounts of rocks, mineral specimens and semiprecious gemstones “Except on developed recreation sites and areas, or where otherwise prohibited and posted.” BLM’s rock-collection FAQ (February 2024) says collecting in national monuments is “Generally, yes” allowed, unless the items are protected objects of that monument or the area is closed.

Carrizo Plain National Monument has its own wrinkle. Its 2010 management plan protects the monument’s fossils, and fossil work there needs a BLM permit. On minerals, the same plan says: “Small amounts of minerals can be collected by individuals from Soda Lake with prior permission obtained from BLM. These individuals will be restricted to use of hand tools to dig through the saline crust.” So the hanksite and thenardite at Soda Lake are closed to walk-up collecting, and a permission-based option exists. The club’s map marks Soda Lake as prohibited, which is the safe reading if you haven’t talked to BLM. The BLM Carrizo page sends visitors to the Goodwin Education Center and the Bakersfield Field Office.

CDFW wildlife areas: look, don’t collect

Big Sandy Wildlife Area near San Miguel is a Type C wildlife area with no entry pass needed. Its page says nothing about collecting, but the statewide rule for all Department lands, 14 CCR § 550(g)(3), bars removing or disturbing “any … soil, sand, gravel, rock, mineral” on Department land, with limited exceptions. Treat Big Sandy as a place to look at jasper and fossils, and leave them there unless CDFW’s Central Region office tells you otherwise.

Big Sur jade: the sanctuary rule

The one clearly legal jade take on this coast comes from marine sanctuary law. 15 CFR 922.132(a)(1) lets you collect jade already loose on the seabed inside Monterey Bay National Marine Sanctuary, from the mean high tide line out to the 90-foot depth line, between the beach stairway at south Sand Dollar Beach and the tip of Cape San Martin. You’re limited to hand tools, lift bags with no more than 200 pounds of combined lift, and what you can carry yourself. That stretch is in Monterey County, north of the San Luis Obispo County end of the coast. Above the tide line, you’re on national forest or private land, and the rules above apply.

The club’s sites, by land status

The list below is the club’s, with its reported finds and land notes. The finds haven’t been checked in the field for this post.

Open national forest land

• Cuesta Ridge. Quartz crystals, geodes, calcite rhombohedrons, chromite, and well-developed slickensides. The West Cuesta Ridge / TV Tower Road area is mostly Los Padres National Forest, so the Forest Service rules above apply. Confirm current rules with the ranger district.

Check ownership and local rules first

• Atascadero. Petrified whale bone, agate, jasper, and marine fossils (pectens, sand dollars) in the gravels and exposures around town. Check who owns the ground.
• Avila Beach. “Deedeeite,” the club’s name for a local stone. City beach and creek: stay off private property and follow tide and park rules. Municipal rules weren’t checked for this post.
• Big Sandy Wildlife Area (San Miguel). Jasper, marine fossils, coal. See the CDFW rule above.
• Big Sur Coast (Ragged Point to Lucia). Jade, gold, garnet, rhodonite, jasper, serpentine. Mixed coastal land; work out whether you’re on a public beach or a private parcel. See the sanctuary rule above for jade.
• Cambria (Moonstone Beach / San Simeon Inlet). Agate, jasper, chert, amethyst, small quartz geodes, cinnabar. Moonstone Beach is a state beach, so the State Parks rule applies. Never collect from the bluffs or closed areas.
• Cayucos. Agate, jasper, and mushroom rhyolite (biconoid fragments) in the beach gravels.
• Highway 41 West gorge. Jade and chromite, west of Atascadero toward the coast. Don’t stop unsafely on the highway, and watch for private land.
• Highway 46 west summit. Biconoids, geodes, mushroom rhyolite. Mixed ownership.
• Nipomo Mesa. Nipomo agate (bean field, sagenitic and marcasitic types), marine fossils, Ice Age fossils. It’s the county’s best-known agate locality, and much of the mesa is private farmland. You need landowner permission.
• See Canyon (Irish Hills). Brecciated jasper. Much of the canyon is private or has limited access; confirm public access first.
• Shell Creek (Highway 58). Classic Miocene shell beds: pectens, oysters, sand dollars, barnacles, snails. Collecting from road cuts can be restricted. Don’t trespass or dig into the banks. County road-cut rules weren’t checked for this post.
• Templeton. Biconoids, petrified whale bone, shark teeth in the surrounding fields and gravels. Check ownership.

Off-limits or hazardous

• Montaña de Oro (Hazard Canyon / Spooner’s Cove). Petrified whale bone and agate are reported here, but it’s a California State Park and collecting rocks, minerals and fossils is prohibited under the State Parks rule.
• Rinconada Mine. Cinnabar and quartz crystals at a historic mercury mine between Santa Margarita and Pozo. EPA’s site profile records mercury in condenser dust, tailings and Mine Creek from a mine that ran from about 1872 to 1968, and describes removal and stabilization work. BLM and the Forest Service jointly manage the workings, and the main processing area is private land. This is not a casual collecting stop.
• Soda Lake (Carrizo Plain). Hanksite and thenardite. Closed to walk-up collecting; see the BLM section above for the permission route.

Arrowheads and artifacts

The club’s list mentions arrowheads at several of these sites. Leave them where they are. Artifacts can’t be collected on national forest land, the State Parks rule protects everything in a park unit, and Carrizo’s fossils and cultural sites are protected under the monument. If you find one, a photo is the only thing to take home.

Before you go

1. Work out who manages the ground: state park, national forest, BLM, CDFW, city, or private.
2. For a state beach or park, ask the unit whether surface rockhounding is allowed there.
3. For Cuesta Ridge, call the Santa Lucia Ranger District.
4. For Soda Lake, contact BLM’s Bakersfield Field Office ahead of time.
5. On private land, including most of Nipomo Mesa and See Canyon, get the owner’s permission.
6. Take small personal amounts, use hand tools, and leave fossils and artifacts alone unless the rules for that land clearly allow them.

The club meets on the second Wednesday of the month at the SLO Senior Center, 1445 Santa Rosa St., San Luis Obispo, at 7 pm, with a juniors session at 6:15 pm. Check slogem.org for current details.