Cornetites are a rare copper mineral from the otherwise prolific copper-mining district of Congo, and partly because of this, along with their striking color palette, they are very popular with collectors. They appear mostly in very small batches of maybe a dozen, with one or two dealers, now and then. This one is spectacular in person due to the richness of the malachite microcrystals which creates all sorts of wonderful hues in combination with the cornetite.