ANOTHER LOOK AT GLASS BUTTE OBSIDIAN

Many people who make cabochons avoid working with obsidian because it is soft and fractures easily. It is a struggle to get the scratches out in the sanding steps and it can be difficult to polish. It took me a while to find the solutions to these problems.

- BOB RUSH

OBSIDIAN TYPES

Obsidian is abundant as a lapidary material but much of it can be considered as unattractive and boring. However, some varieties are rather spectacular as well as being quite affordable. My favorite materials include Glass Butte mahogany with a midnight lace pattern and Davis Creek rainbow obsidian. The collecting sites remain readily accessible and good material is abundant even in larger sizes.

My most recent focus has been on the Glass Butte material. When oriented correctly where the slabs have black areas surrounded by bands of red or brown mahogany color, they can be beautiful and mysterious. This glass material can have some crazy patterns.

SELECTING MATERIAL

In the rough, the black areas do not usually show any patterns. When you are selecting the material, look for a piece where there are bright red areas separated by larger black areas. When viewing the rough material there isn't a reliable method of determining whether the black areas will be dark and opaque or maybe show translucency and semi-transparency. Slabbing it is the only way to be sure.