Fire agate is chalcedony (microcrystalline quartz) that has a play of color similar to opal. The color is in thin layers that are encased in dark chalcedony. Fire agate can be cut into standard cabochons, but when it is carved to remove the chalcedony overlaying the color layer, it really brings out the colorful beauty of the stone. Polishes well with cerium oxide or diamond. Mohs hardness 6.5 to 7.
|