This is a leaf shaped Pseudomorph Agate Cabochon. This one is good for those interested in collecting the many forms of agate, jasper, or as in this case, "other" minerals.

In mineralogy, a pseudomorph is a mineral or mineral compound that starts out as one particular mineral, like aragonite. Over time, that original mineral is replaced by another - in this case agate. The name, pseudomorph, literally means "false form".

Although this is a cab, you can also glue on "bails", or have the piece drilled to accept a pinch bail. Either approach will let you turn this sample into a fine pendant.