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Thundereggs are one of those rocks that make perfect sense once you understand the geology, but at first glance they seem strange. From the outside, they often look like ordinary lumpy nodules. Cut one open, though, and you might find agate, quartz crystals, jasper, opal, or intricate patterns hidden inside. That contrast is what makes them so appealing to collectors.

So how does something like that form?

Continue reading “How Thundereggs Form”

Rabbit Springs, in southern Idaho, is one of those thunderegg localities that tends to be passed around by word of mouth among rockhounds rather than heavily advertised in guidebooks. The area produces rhyolite-hosted thundereggs with agate, chalcedony, opal, and occasional crystal-lined interiors. While not every egg is spectacular, Rabbit Springs has built a loyal following for one feature that makes it stand out: some specimens fluoresce impressively under UV light.

Continue reading “Thundereggs at Rabbit Springs”

The Salmon River area of Idaho is known for producing small but deeply colored garnets that have attracted rockhounds for generations. These garnets are usually found in river gravels, bars, and weathered rock along parts of the Salmon River drainage. Most are dark red to reddish-purple, though some appear almost black until held in sunlight.

Continue reading “Salmon River Garnets”

On the Oregon–Idaho border, near the little town of Nyssa, lies one of the most famous agate collecting sites in the Northwest: Graveyard Point. For over a century, this area has produced agates filled with striking “plumes” — delicate, featherlike inclusions of minerals that look almost like smoke or underwater plants frozen in stone.

Continue reading “Graveyard Point Plume Agate”

Saddle Mountain, in central Washington near Mattawa, is one of the state’s best-known spots for petrified and agatized wood. The ridge runs for miles above the Columbia River, made up of layers of basalt and ash from ancient eruptions. Over time, wood that was buried in those flows was replaced with silica, leaving behind fossils that are now dug out by collectors.

Continue reading “Saddle Mountain Petrified Wood”

Rimrock Lake, tucked into the east side of the Cascades in Yakima County, Washington, is better known as a fishing and camping destination than a rockhounding spot. Still, up in the hills above the reservoir there are deposits of thundereggs—volcanic nodules that draw a handful of collectors each year.

Continue reading “Thundereggs at Rimrock Lake”

For anyone who’s spent time rockhounding in the Pacific Northwest, there’s a good chance you’ve heard the name Nick Zentner. Maybe it was through a YouTube recommendation, a late-night geology rabbit hole, or a road trip podcast where his voice filled in the volcanic gaps between pit stops. However you found him, his lectures and interviews have become a kind of unofficial companion guide to the region’s wild geology—especially for those of us who like to collect a physical piece of it.

While Zentner isn’t a rockhound in the traditional sense (he’s a geologist and professor at Central Washington University), his work has had a real impact on the hobby. He connects the dots between landscapes and deep time, giving context to the strange, colorful, and sometimes frustrating rocks we dig out of the dirt. Whether you’re collecting thundereggs in Oregon, agates in Washington, or jasper in the Columbia Basin, there’s a good chance Nick’s explained the volcanic chaos that made it all possible.

Continue reading “Digging Deeper: How Nick Zentner Enriches Rockhounding in the Pacific Northwest”

When it comes to finding rocks, minerals, and especially thundereggs, few tools are more powerful (or underutilized) than Mindat.org. Built and maintained by the mineral community, Mindat is the world’s largest open mineral database—and it’s surprisingly useful for rockhounds, even if you’re not a crystallography nerd or museum curator. Whether you’re hunting agate in central Oregon or chasing copper minerals in Arizona, Mindat can help you discover spots, identify finds, and plan trips smarter.

In this post, I’ll walk you through how to use Mindat as a rockhound, with tips on reading the maps, finding thunderegg beds, and avoiding some common pitfalls.

Continue reading “Rockhounding with Mindat: How to Use the Internet’s Best Mineral Tool in the Field”

After years of digging, cutting, and collecting, I’m excited to finally open the virtual doors to Cascade Lapidary. What started as a personal obsession with thundereggs, saws, and volcanic mud has slowly taken shape into a proper outlet where I can share some of the stones and stories I’ve uncovered along the way.

This site—caslap.com—is still growing. Right now, it’s home to a small but curated selection of thundereggs and other lapidary materials, mostly from Oregon and Washington. I’ll be adding more soon: rough rock, polished cuts, maybe even some equipment and build guides if things go right. Whether you’re a seasoned cutter or just someone fascinated by what hides inside a dusty old nodule, you’re welcome here.

Check back often—there’s plenty more coming. And thanks for stopping by.