What to Cut: Kokoweef Cave Onyx

By Russ Kaniuth

Kokoweef Cave Onyx, also known as “cave popcorn”, is a stalactite found in the Kokoweef cavern in Southern California. It can be made into some very beautiful cabochons, either in classic shapes or natural, free-form shapes.

I recently spoke to Ralf Meithe, President of the Bullhead City Rock Club and volunteer archeologist at Kokoweef, who gave me some good info on this cave onyx. This material consists mainly of calcite and aragonite, and the formations started to grow as far back as the Jurassic Period (155 mya). There’s also a hidden surprise to this material: if you hold a piece under a UV light, you will see it glow a fluorescent green.

The Kokoweef cavern is closed to the public, but material can still be found either online or at rock shows.

Figuring Out the Pattern

Since the main component of this material is calcite, it tends to be soft, and will cut and shape rather easily. Before cutting your material into slabs, it’s best to figure out what type of patterns you want first. When holding the material in your hands, you will see one end that looks like it’s dripping; that’s the bottom of the stone. If you cut across the top, you can get some really nice cross patterns with smaller floating orbs, but if you decide to cut vertically, you will get some really beautiful flowing patterns in earthy tones, sometimes even with red bands.

I try both approaches, cutting a few slabs from the bottom and then a few from the sides to get a variety of patterns to make cabochons with. Note that, if you cut vertically, there is a tendency for portions to break off.

Once your slabs have been cut, you can figure out what cabochon shapes you’d like to cut, and experiment by utilizing the natural fingers coming down from the stalactites as free-form cabs.

The cabbing process for solid pieces with typical, classic shapes doesn’t need any extra steps; they tend to be very easy to cab. One thing to keep in mind, however, is that the material is generally soft, and starting on a less-aggressive wheel is recommended.

Free-Form Approach

Now, if you plan on trying a free-form cabochon, you can choose to keep the natural edges or form a girdle on the sides. Sometimes, making flat cabs with natural edges can be very aesthetically pleasing to a jewelry designer who likes to mount cabs using prongs. Others will like an average 3 mm girdle to mount, as most silversmiths do.

Either way you do it, this material can be a challenge and a lot of fun to work with. I like to work some of the free-forms with a 3 mm girdle and a dome. When starting out, I shape the bottom into either a “V” shape or a rounded teardrop shape so the designer can securely mount the stone, then I dome over the material cautiously over all the natural shapes and try to keep a uniform dome across the entire stone.

Either way you do it, this material can be a challenge and a lot of fun to work with. I like to work some of the free-form cabs with a 3 mm girdle and a dome. When starting out, I shape the bottom into either a “V” shape or a rounded teardrop shape so the designer can securely mount the stone, then I dome cautiously over all the natural shapes, trying to keep a uniform dome across the entire stone.

Kokoweef Cave Onyx can be polished to a mirror shine without much effort and without the need for any additional polishing compounds.