Though this is not a copper based mineral oxide it can fit into that group. The piece is very heavy for its size and has nice deep gun metal color. But it is a softer stone so care needs to be taken on setting and the type of setting. It has a nice chip on the back side girdle.
Visit my Sold cabochon Gallery to see past opals I have cut. You will find other examples of materials, shapes, sizes, colors, and in general see my work there. Some stones date back over 15 years in there. I don’t show everything I cut, just the ones I really liked over the years. Please let me know if you have any questions about those materials.
Its also important to visit your local rockclub if you have one near by. Its a great place to start if you are new to gems and minerals. Thank you.