Oregon is made for the curious! I want to know everything when traveling the wide-open spaces of Central Oregon.

That’s how it was when we recently headed south on US 97 searching for the forty million years of geologic history found in the Oregon State Rock called “Thunder Eggs.”

As a child, I collected and cherished the magical, mysterious golf ball size rocks for their drab exterior, but their oh-so-creamy and colorful agate interiors.

Thunder Eggs continue to be prizes for young and old rock hounds alike.

Technically a thunder egg is not a rock: it’s a nodule or a geode that forms inside other rocks. Yet, if you were to judge by the throngs of visitors who stream through the Richardson’s Recreational Ranch, just off US 97 near Madras, thunder eggs are without question the most popular rock in Oregon.

View Gallery: Thunder Eggs

The expansive seventeen-thousand-acre ranch allows rock hounds the opportunity to dig and discover countless secrets in the soil.

On a recent visit to the ranch, Casey Richardson, co-manager of the expansive operation, led us across seven miles of bumpy back road to a mother lode akin to thunder egg heaven on Earth.

Casey Richardson’s family used to raise beef across their impressive spread, but decades ago they had a different idea. Now, Casey co-manages the family property – not for livestock - but for the dirt under-foot:

“We do what everyone else comes for vacation to do, so how can you not like that,” said Richardson with a wry smile.

We arrived at the southern end of what is known as the “Blue Bed;” the oldest and most productive thunder egg site on the Richardson Ranch for the past four decades.

Casey said that here, it’s all about the “gas,” but not the kind you pump.

“Thunder eggs are gas bubbles that formed in a rhyolite formation between thirty and forty million years ago,” noted Casey.

He teasingly declared that all you need to make a thunder egg “is a volcano that produces lava rich in silica, the stuff of which quartz is made. As the lava cools, steam and gases trapped within the lava form bubbles. The beauty is in the bubbles.”

Armed with rock hammers, shovels, and insatiable appetites for the unexpected, Chris and I were anxious to do some digging in the dirt--and it didn’t take long to hit pay dirt.

The technique isn’t too difficult: simply kneel down and hammer, scrape, chisel, and mine the dirt away from the egg.

“Rockhounds love to get dirty,” declared Casey.

So bring a bucket, gloves and rock pick (Richardson’s provides a bucket and rock hammer for your use) to dig Oregon’s treasured state rock from the dirt.

Thunder Eggs became Oregon’s official State Rock in 1965 and they are small as marbles but can reach basketball size.

“Each one of them is different and if you dig a couple thousand pounds like I have, you go home with quite a feeling of accomplishment. It’s a ton o’ fun," said the smiling Casey Richardson.

Filling a five gallon bucket is no sweat and didn’t take us long – then the real fun began back at the rock shop.

Casey’s lifetime of experience knew just the right angle to make a slice through one of our eggs with a diamond embedded saw blade and reveal the rock’s interior.

Thunder eggs were first discovered in this area during the 1920s by a rancher named Leslie Priday. For the past 40 years, the Richardson family has owned and operated its recreational rock ranch for eager tourists who can dig their own treasures or purchase them inside a small lapidary shop.

When they are cut open, they reveal agates of various colors and exquisite designs that stand out when they’re polished.
As we waited for the automated saw blade to slice open all of our prizes, Casey showed off his most valuable thunder egg called a “Priday Plume.”

He called it “one in a thousand” and it was easy to see what he meant for it looked fabulous with varied hues of blues, greens and reds.

He proudly noted, “It’s unique for its size and how clean each plume is. It’s a phenomenal piece.”

Richardson’s displays inside the shop are real show-stoppers too with rows of gorgeous thunder eggs and other exotic-looking rocks from across the world.

You’ll discover that thunder eggs can be made into beautiful, varied jewelry, especially pendants, pen stands, and bookends.

Family photos show off four generations of Richardson’s that have kept the business moving forward.

Meanwhile, back in the work shop, Casey said it’s the surprise of it all that continues to excite him.

Once a rock is cut open, each provides a lasting memory of time well spent in the Oregon outdoors.

“The really neat part is that when you dig up a thunder egg and bring it down to have us cut it open, you’re the first person to have ever seen that rock. And to think it took sixty million years to make it, plus there’s no two alike, they’re all different--and the next one is going to be the very prettiest one you’ve ever cut.”

I discovered that the simple beauty and complexity of these geologic wonders are best appreciated when the egg is carefully cracked open and placed on display to reveal a moment from a distant past that’s been frozen in time.

The sanding and polishing reveal depth and features that are beautiful and unique – just like the state that the rock represents.

“Everybody likes to get outdoors as a family and do something together,” said Casey Richardson. “Maybe you get a little dirty digging in the ground. But you get to take your prizes home, and a five-gallon bucket of thunder eggs only costs about twenty-five dollars. That’s not bad for a day together.”