Carmody Lake
Wyoming
Find: Sweetwater Agates, chalcedony, low quality amethyst
GPS: 42.57957, -108.24366
Nearest city: Casper, WY
Recommended Vehicle: Car may be possible, but 4x4 Recommended
Season: Accessible year round, Winter is likely to have significant snow, ice, and frigid temperatures.
Summary:
Wyoming’s Sweetwater Agates are a variety of dendritic agate that are found in the Sweetwater River basin. For lack of better description, it is a wonderfully empty portion of Wyoming. To ensure I didn’t see another soul out here, I visited during the Winter and it was chilly.
The agates themselves are one of the less visually striking stones I’ve gone rockhounding for, if I’m to be completely honest. Comprised of chalcedony, they have dark dendrites similar to a fern-leaf in appearance.
I think you need a cut and polish on these to appreciate their beauty in regular light.
However, the reason I went out here is because Sweetwater Agates contain trace amounts of uranium. It causes a green fluorescence under UV light. There were also some faintly purple, scrappy pieces of weathered amethyst I found in the area too.
The gravel roads that wind through the public land alongside Carmody Lake weren’t too bad. You could probably make it out here in a regular car if you really wanted to, but 4x4 makes for better peace of mind.
Video
Check out the video to best see what can be found when exploring this spot.
3 Helpful Tools
Water Bladder
The warmer months are arid and dry in Wyoming. A water bladder is a great luxury to hike with, but the plastic tube will freeze if you’re out in Winter.
Geology Pick
A geology pick is useful for flipping over embedded stones and prying them out of the ground.
UV Flashlight
Honestly, if I were to do this over, I’d come back with a friend or two at night and cover a lot of ground with longwave UV lights. Winter in Wyoming is great for a lot of things, but rockhounding isn’t one of them.
The ice patch behind my vehicle is what I believe is Carmody Lake itself.
I scoured the washes like this to try and find large accumulations of rock.
This was my best guess as to what a Sweetwater Agate looked like in daylight. Most pictures of them online are after they've been cut and polished, so it was tricky for me - at least as a total novice to the area.
Here is the "amethyst" if you want to label it that. Really, I think quartz with some impurities is a better way to describe it.
These photos were taken under 365nm UV light.
The greens were my favorite, which is caused by the trace uranium content.
I also happen to collect uranium slag glass.