Can anyone venture a guess as to what minerals are in this rock? I’ve had it for years and have never been able to identify it. I believe I got it somewhere in Northern California but it was from a vendor so I don’t know if it is native or not. It’s been formed and polished into a marble shape but the back of it is pitted. It is dark green with a brown circle and white ring. The white ring around the brown has circular satellite spots.
closed as primarily opinion-based by Fred, trond hansen, Peter Jansson, Jan Doggen, Spencer Dec 27 '18 at 15:21
Many good questions generate some degree of opinion based on expert experience, but answers to this question will tend to be almost entirely based on opinions, rather than facts, references, or specific expertise. If this question can be reworded to fit the rules in the help center, please edit the question.
That is probably ocean jasper.
It has distinctive concentric circular patterns.
What is Ocean Jasper?
Ocean Jasper is a trade name for a multicolored Madagascan stone with spherical patterning set against a contrasting background color. Although called a jasper, the stone is actually a mixture of different forms of quartz: clear and colored varieties of chalcedony, banded agate, and pockets of tiny quartz crystals called druzy. When examined under a polarized light microscope, Ocean Jasper becomes chalcedony spheres floating in a sea of chalcedony.