Rockhounding for Rim Jasper

A story by John Gaumer

While reading our favorite rockhounding guide, California Gem Trails, I learned about a cave just outside of Prineville, Oregon. The cave was rumored to be inhabited by bats but also a source of beautiful jasper. Rim Jasper, as it’s known, forms in layers of tan and brown colored material, much like a chocolate and caramel layer cake.

It was the late 1960’s, and the early days of our business. In those days, my dad and I would often go to Prineville, Oregon, to buy inventory, or to hunt for rocks. On one such trip, we stopped at Quant’s Rock Shop, owned by a man known as “Shirts”. While there, we chatted about the bat cave. He told us it was located above Ochoco Lake, so off we went.

Polished nodule of Rim Jasper mined near Ochoco Lake, Oregon
Polished nodule of Rim Jasper mined near Ochoco Lake, Oregon
The bat cave was set high into the cliff face. We searched the talus below the cave and found a few loose pieces of jasper, but we knew the good stuff was likely to be inside. My dad couldn’t scale the cliff to get into the cave, so I climbed up alone.

The mouth of the cave had already been mined, so I explored the back of the cave. There were bats hiding in the crevices of the cave and I could hear them squeaking. The cave had low clearance, it was dark and I didn’t have a flashlight. I started to get claustrophobic and headed to the mouth of the cave to regroup.

I noticed some soot stains on the ceiling of the cave and decided to start a fire to light up the back of the cave. Very quickly, it got very smoky, but I headed into the back of the cave anyway. By firelight, I mined on my belly with my back pressed to the ceiling. I struggled to work out 25 to 30 pounds of material before I needed cleaner air. As a side note, don’t start a fire in a small enclosed space. Mining by firelight in a bat cave was, perhaps, not my smartest moment.

We got our treasures back into the car and headed home to California. Over the years, we’ve been able to turn that lovely rim jasper into custom jewelry and museum pieces. Stop by our museum to see our favorite treasures up close.

Rim Jasper cabochons and museum pieces