Thundereggs – Richardson Rock Ranch, Madras, Oregon

If you like rocks–even a tiny bit–then you have to hunt for thundereggs with your kids.  We made it our summer “Grand Adventure” in August 2014 and had a blast.  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!

Drive north to Madras through the bucolic farmland.  Green grass, red barns, and black & white cows abound.  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.

Scenery on the way to Thundereggs


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.

The road to Richardson Ranch for 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 thundereggs


I took the rock hammer and wandered a bit, picking here and there.  Around the corner, away from the crowd, we found our spot.  

It was easy to dig for thundereggs, and our kids found a ton of them.
Our rock hounds included our two older kids, plus my daughter’s friend.


We traveled this trip 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 a thunderegg out of the rock
My son, age 3, digging out a thunderegg.

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.



Pointing to a thunderegg still in the rock
A round, orange-sized “egg” peeking out of the rock.



A chunk of rock with a broken thunderegg embedded.


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.
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.
Examples of thundereggs


Thundereggs cut open


Look past the goofy family and you can see their large rock yard…incredible rocks from all over!



Cost: $1 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)
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
Gear needed: sunscreen, rock hammer (or chisel & hammer), shade, water.  Some areas stroller friendly, other areas better for a baby carrier.


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 very often on dry winter days) is getting outdoors and finding adventure.

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