Oregon Thundereggs – Richardson Rock Ranch, Madras, Oregon

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If you like rocks–even a tiny bit–then you have to hunt for thundereggs with your kids.  The best place in Oregon to find thundereggs is at Richardson’s Rock Ranch near Madras, Oregon.  Getting there is easy and the prices for collecting and cutting are reasonable.

Thundereggs are Oregon’s state rock.  They’re orange-sized mud balls that, over time, filled with layers of agate.  Colors vary widely and they can sometimes contain crystals.  A few pictures online and we were hooked.  We had to go get some thundereggs for ourselves!

Travel to Madras through bucolic farmland.  Green grass, red barns, and black & white cows abound.  You’ll want to stop for photos, and you absolutely should!  Also stop in Madras for bathroom breaks and to fill up on water and snacks.  The shop at Richardson’s Ranch has a few things, but mostly they sell rocks.

Oregon Thundereggs - beautiful scenery

Richardson Rock Ranch

As we made the turn into the Ranch, the terrain changed into an arid moonscape.  We wondered what other treasures were under the rocky soil, besides thundereggs.  If you’re going with kids, be sure to ask at the shop which pit has the easiest digging.  A friend went the same summer as we did, and ended up in a “pro” pit where the digging is much harder, but the chances of finding something really special are higher.   Different pits have different payouts, and different skill levels.

The road to Richardson Rock Ranch for thundereggs

Digging Oregon Thundereggs

We were in a hurry to get to the digging grounds, so we stopped at the ranch store and got directions and buckets.  Then we headed out and wasted no time setting to work.  We didn’t really know where to start, so we just followed the crowd and dug with everyone else.  We found a couple right away, but I was hoping for more fertile ground.

Our kids digging Oregon thundereggs at Richarson Rock Ranch

I took the rock hammer and wandered a bit, picking here and there.  The pits are large and somewhat meandering, and any place is fair game.  Around the corner, away from the crowd, we found our spot.  

Oregon Thundereggs - digging can be easy at Richardson Rock Ranch
Our rockhounds included our two older kids, plus my daughter’s friend.  They had no trouble digging thundereggs out of the soft, sedimentary rock.


Richardson Rock Ranch thundereggs - digging pits and traveling with kids
We traveled with two babies, one a little over a year (but not walking) and one just 5 months old.  My husband set up a blanket, umbrella, and sat with the babies while I hunted around with the big kids.


My young son demonstrates how to dig Oregon thundereggs out of the rock
Our son had no trouble digging out his own Oregon thundereggs.

In this spot, thundereggs were plentiful and very easy to dig.  Even our 4-year-old son had no trouble nudging them out of the rock with the rock hammer.  Here’s a very short video showing how easy it was to find them!  The rock is very soft and sedimentary; it really is rock, but crumbles like dust when tapped with a rock hammer.


Oregon thundereggs - where to find them
A round, orange-sized “egg” peeking out of the rock.


Oregon Thundereggs are fun for kids to find


Oregon thunderegg agate
A chunk of rock with a broken thunderegg embedded.


Dig Oregon Thundereggs at Richardson Ranch
Our family (minus the two babies chilling in the air-conditioned van, just a step away) at the South Blue Beds at Richardson’s Rock Ranch.

The Ranch Store

We stayed for about an hour and half-filled a 5-gallon bucket.  We had plenty, so we packed up and headed back to the ranch store, which is amazing all in itself…it’s a vast warehouse of rocks, both natural and polished.  Some are found right on the ranch, others are imported from other locations.  The ranch also has cutting services, so you can have your thundereggs sliced open for a nominal fee before you leave.  Cutting rocks does take time, so plan ahead and be back to the store well before closing time.  On very busy days, the wait can be even longer.  We visited on a weekday, and there was no line at all.
Examples of thundereggs

Oregon Thundereggs that we dug at Richardson Ranch


Thundereggs cut open

Some of our thundereggs after they were cut open. I love the lines of color in some of these! A couple are even vaguely Oregon-shaped.

Beautiful colors in Oregon Thundereggs

Our double thunderegg from one of the photos above showing beautiful red and maroon stripes once it was cut.

Richardson Ranch rock shop
Look past our sun-drenched family and you can see their large rock yard…incredible rocks from all over!


Richardson Ranch's rock yard

The rock yard at Richardson Ranch – so much more than thundereggs!


Cost: $1.25 per pound (10 lbs minimum), plus cutting fee at $0.35 per inch.  It cost us less than $20 to cut open all of our rocks (about 1/2 a 5-gallon bucket)  More info here.
Amenities: water, snacks, popsicles, porta potty, lots of rocks and rock souvenirs.  Rock museum.
Our kids ages at the time of visit: 9, 4, 1, and 5 months


I’m a middle-aged mom of 3-6 and sometimes more, depending on day. I’m out of shape and usually exhausted. Our favorite summertime activity (and often on dry winter days) is getting outdoors and finding adventure.

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