Rockhounding San Mateo County, California: 13 Places to Hunt Rocks, Crystals, and Fossils

San Mateo County, California, is an ideal location for rockhounders who love the ocean and all the treasures the ocean brings.

There are a few locations for rockhounding in San Mateo County itself, and if you’re willing to drive an hour north, towards San Francisco, or south, toward Santa Cruz, you’ll be able to find even more.

This blog gives you a list of where to go, what to know, and what you can find.

While caution is always encouraged, most of the locations are suitable for families with kids. 

Rockhounding San Mateo County, California

Disclaimer

The information provided in this article by YesDirt.com 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.

Here are the first five locations.

These are all within San Mateo County, and are 10 minutes to half an hour away from each other.

1. Coyote Point

What you need to know about this location

  • There is a $6 entry fee per vehicle
  • Dogs are welcome on trails
  • Best places for rocks will be north of the yacht harbor

What you can find

  • Agate
  • Chalcedony
  • Jasper
  • Moonstone
  • Cinnabar
  • Apophyllite
  • Gyrolite
  • Petrified wood
  • Chert

2. Crystal Springs Reservoir

What you need to know about this location

  • The best place for rockhounding will be on the western slope of the reservoir
  • There is a parking lot and public restroom along Skyline Boulevard
  • Dogs are not permitted on the trails

What you can find

  • Agate
  • Chalcedony
  • Jasper
  • Moonstone
  • Petrified wood
  • Chromite, as scattered masses

3. Pascedero State Beach

What you need to know about this location

  • Parking is available, but not free
  • Restrooms available
  • No dogs allowed
  • Best and safest time to go is at low tide; the rocks can be slippery or completely covered otherwise
  • Head a bit south of the official state park in order to collect, since you cannot collect from the state park itself

What you can find

  • Agate
  • Jasper
  • Carnelian

4. Montara Mountain Trail

What you need to know about this location

  • This is a 2.1-mile hike
  • The topography can get pretty steep at times, so plan accordingly 
  • Highest elevation reaches 1600 feet
  • Not the best for young kids

What you can find

  • Limestone
  • Granite

5. San Bruno Mountain

What you need to know about this location

  • There is a $6 entry fee per vehicle
  • No pets allowed
  • Elevation reaches from 250 feet to 1,314 feet

What you can find

  • Graywacke
  • Quartz
  • Feldspars
  • Pumpellyite

There are four locations to the south, 45 minutes or less away from San Mateo County.

6. Alum Rock Park, San Jose

What you need to know about this location

  • Parking is metered, $6 per day
  • No dogs allowed, as Alum Rock Park is a protected wildlife sanctuary
  • Best place to look will be among and around the boulders

What you can find

  • Alabandite
  • Hausmannite
  • Tephoroite

7. Guadaloupe Creek, Almaden

What you need to know about this location

  • Roughly 45 minutes south from San Mateo
  • It may be helpful to insert coordinates into your GPS to find this location, as the river covers a lot of territory – 37°12’29.0″N 121°54’04.6″W
  • There are no defined trails

What you can find

  • Dendritic agate
  • Chert
  • Jasper

8. Area Mines near New Almaden

What you need to know about this location

  • Also located in Almaden, this is another location where coordinates would be helpful – 37°10’33.6″N 121°49’14.9″W
  • Located off of Bertram Rd
  • No defined trails

What you can find

  • Chert
  • Cinnabar
  • Apophyllite
  • Gyrolite
  • Jasper

9. Creeks near Morgan Hill

What you need to know about this location

  • Northwest of Morgan Hill in Santa Clara, CA, is a bit of forest with some good finds around Uvas Creek and Sycamore Creek
  • Since there are no defined trails or locations, use these coordinates: 37°03’18.3″N 121°39’49.1″W
  • You’ll be trekking behind Cottage Creek Vineyards, for a landmark

What you can find

  • Poppy Jasper, often referred to as Morgan Hill chert

There are two locations about an hour north of San Mateo County, in or around San Francisco.

10. Outcroppings alongside Lands End Trail, San Francisco 

What you need to know about this location

  • About 45 minutes north of San Mateo 
  • Lands End Trail is a moderate hiking trail along the bay with views of the Golden Gate Bridge
  • Follow the trail to the rock outcroppings above the bay
  • Caution is advised along the uneven rocks
  • Parking available at the start of Lands End Trail
  • This is a very popular spot around sunset

What you can find

  • Spherulitic Chert
  • Jasper 

11. The Area around Fort Point, San Fransisco 

What you need to know about this location

  • This location is about an hour north of San Mateo County
  • A historical site very popular with tourists, especially around sunset
  • Parking and bathroom available
  • Pets are allowed on grounds, but not inside any buildings

What you can find

  • Diabase
  • Datolite
  • Basalt
  • Apophyllite
  • Aragonite
  • Barite
  • Calcite 
  • Chert
  • Jasper

These last few sites are known specifically for their fossils, though some interesting rocks have been discovered there as well.

12. Beaches at Half Moon Bay

What you need to know about this location

  • Only 20 minutes from San Mateo
  • Half Moon Bay has quite a few beaches where fossils have been found
  • I would not recommend collecting from Dunes Beach or J.V. Fitzgerald Marine Reserve, as those are state protected beaches
  • Parking is available by Poplar Beach

What you can find

  • Fossilized sand dollars
  • Large animal vertebrae
  • Scallop imprints

13. The Pursima formation at Capitola, Santa Cruz

What you need to know about this location

  • Just about an hour south of San Mateo
  • To find, take Bay Exit off of Highway 1 until you hit the beach
  • Public parking available ½ mile from beach
  • Be very aware of the tides, as you don’t want to get caught there at high tide
  • Do Not dig into the cliffs to retrieve fossils – this is illegal and dangerous due to erosion
  • This site is less kid friendly, only due to the hazards of tides and falling debris from the cliffs

What you can find

  • Bivalves
  • Gastropods
  • Sand dollars
  • Whale bone
  • Crabs
  • Occasional shark tooth

That’s all I have for you today!

While you’re hunting up some great treasures, please be aware of the land and keep in mind that state parks discourage collecting and disturbing the environment.

I hope this blog was helpful. Have fun and enjoy your hounding!  

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Rockhounding San Mateo County