Geological Snowflakes

Despite my native Oregonian status, I had never seen a thunderegg before. I didn’t know that Central Oregon is known as the rockhound capitol of the world, and that it is home to the largest thunderegg deposits on the planet. In fact, I could fill a thunderegg with everything I knew about thundereggs. But I love to be outside, and I like to play in the dirt, so when I was asked to go rockhounding for Oregon’s state rock it sounded like a pretty good time to me.

Thundereggs are agate-filled nodules found in layers of rhyolite lava flows. About the size of an orange, thundereggs are dull and lumpy on the outside and pretty underwhelming. However, once sliced open, thundereggs reveal unique patterns of colorful minerals encased inside. They may contain simple deposits in layers or intricate and vibrant patterns reminiscent of ancient floral arrangements. Geologists are still unsure about how they formed, but according to local Native American lore, these egg-shaped stones were projectiles thrown by fighting “Thunder Spirits” who dwelt on Mount Jefferson and Mount Hood. When thunderstorms occurred, these two rival spirits hurled the spherical rocks at each other in a fury, scattering them across the Central Oregon desert. So it made sense that I would be hunting thundereggs after a week of stormy spring weather.


I arrived at Richardson’s Rock Ranch, located north of Madras, and the home of the Priday Agate Beds, on a warm and hazy day. Priday was a cattle rancher who discovered the agate beds and opened them up to public digging in the 1920s. After purchasing the cattle ranch in the 1970s, the Richardsons decided to disperse the herd, lease part of the land to other cattle ranchers and focus their attention solely on the business of rocks. “We opened the rock shop and museum on Memorial Day weekend 42 years ago and we haven’t been closed a day since,” said ranch matriarch Bonnie Richardson.

Pulling up in front of the shop, I was mesmerized by the quantity and quality of rocks on the premises. Huge piles of exotic rocks and thousands of thundereggs excavated right on the property were spread out everywhere. I was greeted by Bonnie, who graciously went over the rules with me and showed me on a map where I could dig and what I was digging for. The Priday Agate Beds are composed of six different beds that range in digging difficulty from easy to expert—I chose easy. Bonnie handed me a rock pick and a five-gallon bucket and I headed east down a winding gravel road. Several miles and three cattle gates later, I reached the “rockhounding for dummies” site, more commonly known as “South Blue Bed.”

With my superior rockhounding equipment I commenced digging in the moist perlite lava. Within moments I had unearthed my first thunderegg. The thrill of discovery kept me picking away through layers and layers of ancient soil, content with the repetitive motion of my pick striking the earth, punctuated by the periodic unveiling of another thunderegg. It was extremely meditative. After an hour-and-a-half of digging I had filled a third of my bucket and decided to call it quits. I was eager to get back to the ranch and crack open my eggs.


“Doing the cutting is my favorite part of thundereggs,” said Bonnie. “There’s always that moment of anticipation right before you cut it open. Even if you’ve cut open 10,000 eggs, opening them up for the first time never gets old because each one is unique.” The thundereggs I selected for cutting were brought out to me, carefully held together so that I would be the first one to see what was inside. “The presentation is the best part,” Bonnie said excitedly as I opened my eggs. Just like snowflakes, each thunderegg was distinct. One contained layers of opalite and agate in the shape of Oregon, another revealed white agate shaped like a smooshed starfish. My favorite boasted dark purple and blue agate with a triangular hollow in the middle, exposing light blue crystals. “Ooh, that’s a rare one,” admired Bonnie when I separated its two halves.

In that moment it became clear to me how the Richardson’s world-famous agate beds attracted so many people from all over the world—allure and intrigue are built into every thunderegg. “I never get tired of them,” said Bonnie. “The beauty of the different rocks strikes me.” I couldn’t have agreed more.


More Information

Richardson’s Rock Ranch store is open year round, and the digging beds are open from late April until October. Digging is “weather permitting,” and you must arrive before 3 p.m. Take U.S. Highway 97 north from Madras for approximately 11 miles, where you’ll see a sign for the ranch at milepost 81. From the Highway, follow the signs to the ranch (approximately three miles).


Richardson’s Rock Ranch
6683 Hay Creek Rd., Madras

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