Dishpan Butte to Cedar Rim

- Dishpan Butte and Cedar Rim Area

Last fall, I had my heart set on coming here, but snow and mud played spoilsport. Well, today’s a whole different story. The temperature’s soaring past 90°F, the sky’s a brilliant blue, and it’s bone-dry and oh-so-dusty. The dust, like chalk dust, is relentless—white, fine, and manages to find its way into every nook and cranny.

Memories

- That’S Me A Few Dozen Miles South And More Than A Few Decades Earlier Near Dishpan Butte

This place holds a trove of memories for me. I can vividly recall cruising through this country as a toddler when the only road was a single-lane dirt trail. Later, it was biking around, rock hunting, and eventually the era of guns, hunting rabbits, deer, and antelope. Fast forward to my stint as an exploration geologist, and now I find myself back in this familiar territory, on the lookout for fluorescent rocks.

Over the years, despite the changes—paved roads, energy, and mineral development—the geology here remains untouched. The same Tertiary rocks that make Casper a hotspot for fluorescent rocks are right here. Unlike Casper, though, this area has seen its fair share of rock collecting. From commercial endeavors in the late 1800s to claims spurred by a ’new’ opal discovery in the early 2000s, it’s been a hub of activity.

Back then, fluorescent minerals from New Jersey set the standard, and Wyoming opal was deemed dull and worthless. The opal fluoresces in a blue-white hue, with chalcedony adding the typical uranium green glow. Even a non-fluorescent black manganese dendrite makes an occasional appearance, providing a unique contrast.

But back in the day, the New Jersey minerals stole the show. Wyoming opal wasn’t on anyone’s radar. Its fluorescence didn’t intrigue me much, but the prospect of finding precious opal kept me searching, despite decades and miles passing without a hint of that elusive color.

Today at the Butte

A quick drive down the asphalt gets me within a few miles of Dishpan Butte. Navigating the area on an old trail takes me to its base, and even an SUV can effortlessly get there now.

- At Dishpan Butte, Distant Cedar Rim, And Agate Flats And The Granite Mountains Near The Horizon

Wandering around is refreshing. The solitude and panoramic views are fantastic, but when it comes to rock hunting? Well, let’s just say it’s a bit pathetic! There are hardly any rocks larger than a thumb once you venture beyond the Butte’s talus slope. Everything is the same soft volcanic tuff and ash. The only interesting rock I stumbled upon was this lichen-encrusted one.

- Lichen Encrusted Rock

Lichens can be surprisingly fluorescent, often rivaling minerals. But this one is staying put. It’s been part of this desert for centuries, and disrupting it would be both a threat to its existence and downright shameful.

Not much else to see here. Time to explore elsewhere.

Cedar Rim to Beaver Rim

Cedar Rim is easily accessible with a wide gravel road running through its center. There’s more erosion, exposing more material than around Dishpan Butte. Same white, chalky, and sometimes more siliceous rocks, along with opal prospect pits from a boom that’s now a bust. Driving the rim from south to north, though, didn’t reveal a single outcrop that produced anything interesting.

I knew this area like the back of my hand. As a kid, I’d find chunks of opal here, but not anymore. Not in the road cuts, pipelines, or draws. Anything obvious is gone. You’d need a backhoe to find something worthwhile. This area has been picked over entirely. It’s vast, and while there are probably some rare, barely exposed specimens, you’d wear out a pair of boots searching for them, not trip over or bash oil pans like in my youth.

- Beaver Rim Near The North End Of Cedar Rim

Like many adventures, this one brought back good memories and lifted my spirits. But when it comes to finding interesting rocks in the Tertiary White River near Dishpan Butte, it was a complete flop.

I had plans to spend a few days prospecting for opal and night prospecting for fluorescent rocks, but alas, it’s not meant to be. I’ll head back home, away from this relentless dust. I’ll save my energy for another day, maybe below Beaver Rim. With its erosion and varied geology, it might prove more remote, more productive, and more interesting than anything on top of it. A new adventure awaits next year. ✨

Cheers,
D 🪨🔥