Rockhounding Marin County, California: 5 Places to Find Rocks, Crystals and Fossils  

For rockhounds in the Bay Area, a unique experience is yours to have.

While many might see the cityscape and forested neighborhoods as an obstacle, San Francisco invites the adventurer with an open mind.

These are five gorgeous locations where you could get lucky in Marin County.

Rockhounding Marin County, California


The information provided in this article by is for informational purposes and is subject to change. Laws are updated. Accessibility guidelines and restrictions change. Be sure to confirm the land status and collection rules before you travel to an unfamiliar location or collect any material.

Marin Headlands

The Headlands sit on a literal bedrock of geological history.

Any rockhound interested in the science of rocks will find a wealth of information from the rock here. 

The rocks that can be found at this location are mainly pillow basalt, red chert, and sandstone.

This particular mix of stone is not here by chance. It once existed far beneath the ocean’s surface as the Farallon Plate.

The Headlands and the jutting out of the Farallon Plate were caused by the pushing closer together of the Pacific and North American plates millions of years ago.

Today, if you’re in Marin County, the Headlands are just 40 minutes of cozy driving away.

If you’re heading to this location, you’ll want a car because of the large area you get to cover.

However, if mountain biking and hiking are more your speed, the Headlands are ready for adventurous exploration.

With views of the wide-open sea, the history of all the rocks you’ll find, and the chance to trek through land that hasn’t been explored, the Marin Headlands warmly welcome all rock-hounding visitors.

Mount Tamalpais

Just like the Headlands, this location is also a direct result of San Francisco’s unique geological history.

Climbing a mountain may seem like no mean feat, but for the rocks and the sights, Mount Tamalpais is well worth it.

This mountain sits in Marin County and is formed of the same material that can be found in the Headlands.

Beyond these options, for the rockhound seeking serpentine and radiolarite, or radiolarian chert, the West Peak of the mountain beckons.

However, if you’re up for the walk and you can be tempted by superior ocean views, findings of quartz have been reported on the East Peak of Mount Tam (as it has been fondly nicknamed).

For the climb and the walk, proper gear ought to be prepared for this trek.

Traveling to the mountain demands a car and access to the mountain is reserved only for the day. (Sorry, night owls!)

An important warning to note is that sometimes the upper mountain is closed due to fire danger alerts.

It is possible that during these times, public access to the park is also suppressed for the safety of everyone.

There is no entry fee to enter this park. Activities organized by local exploration groups do, however, draw a fee.

Be sure to check and double-check as you plan your visit to this majestic location.

Agate Beach

If the rockhound enjoys sandy beaches and hunting rocks, crystals, and fossils, this location invites both.

Known for the crystal pebbles which can be found with ease here, Agate Beach does not demand a long trek.

All the rockhound needs to travel out to the location is a car.

After a smooth half-hour drive, the saltiness of the waves and the sure chance of finding serpentine and a gorgeous variety of chert will keep you going once you get there.

The possibility of stumbling upon a marine fossil is also great at Agate Beach.

This comes as no surprise: a short drive away is the Bolinas Lagoon, famed for its fossilized sand dollars.

Returning to the beach, however, one can scour this heavily pebbled beach for the kind of rocks that tickle their fancy.

Once you’re all tuckered out and satisfied with your finds, a beachside picnic probably wouldn’t be a bad idea.

Visitors are invited to arrive at low tide for the best findings.

A $2 fee is also charged for parking. Either way, Agate Beach allows a fun day of rockhounding and leisurely fun.

San Rafael

Warm and sunny, this location already sounds like a fantastic place for a walk through nature.

The rocks that can be found here are graywacke, sandstone, and chert.

San Rafael also holds a great geological formation including limestone and quartz.

Besides this selection of stones, greenstone, a metamorphic rock, is also available for the keen eye.

With such a varied array of stones, any seeker traveling here will find something that piques and satisfies their curiosity.

San Rafael is also accessible through most modes of transportation, so don’t worry about boats or hiking gear here.

Caution must be taken, though, not to stroll onto one of the various mines which populate the area.

But, that said, San Rafael is family-friendly, and even younger rockhounds would find it appealing to explore and hunt in this area.

So, if you’re careful and you keep your eyes open, San Rafael has a world of riches to offer.

Angel Island

Yet another island calls all rockhounds in Marin County to visit.

Findings of glaucophane and jadeite have been reported at this location.

More graywacke is also present here for finding.

Don’t let the pretty name fool you.

Much of San Francisco’s history can be seen while exploring the island.

This island has seen its fair share of tough times, once serving as an active military reserve all the way through to the Second World War.

The history buff rockhound will find themselves surrounded by sights, sounds, and rocks that are greatly desired.

As far as islands go, Angel Island is huge; you will want to give yourself enough time to go hounding these rolling hills.

Accessing the island is possible, but you’ll need a private boat.

If a boat is not accessible to you, the public ferry also allows people to reach the island.

Take one of the hiking trails if it tickles your fancy, but if you prefer an easy time, the parklands on the island are a gorgeous space to pick a spot.

Settle in and see to what treasures nature will guide you.

These Marin County locations promise more than rockhounding. Their unique geology ensures a refreshing, surprising trip for any rockhound willing to dare.

California Rockhounding Resources

If you like to have a physical book in hand (like when there’s no cell service), here’s a few popular options:

Rockhounding California: A Guide To The State’s Best Rockhounding Sites

Gem Trails of Southern California

Gem Trails of Northern California

Smithsonian Rocks and Minerals Identification Guide

Disclosure: These are links to Amazon. As an Amazon Associate, I may earn a commission from qualifying purchases at no additional cost to you.

Wrap Up

The desert and mountain region is one of the best places to rockhounding. 

We have a trip to go rockhounding near Sacramento planned soon, we’ll let you know how it goes!

Let’s start digging!

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Rockhounding Marin County