This Specimen has been sold.
4.2" Polished Black Opal Sphere - Madagascar
This is a large 4.2" black opal sphere crafted in Madagascar. The stand shown in the photos is included with your purchase.
"Black Opal" is a trade name for a variety of an amorphous, black-brown silica mineral, which in this case is collected from Madagascar. This material doesn't have the opalescent effect that you would see in high quality hydrated amorphous silica (opal), but is has it's own beauty.