A huge specimen of black tourmaline overgrowing a large matrix of feldspar, coated on one side by a chalky carbonate (could be removed, if you wish, with acid). The piece is actually quite pretty as is, though - the contrast makes it more visually appealing, to me, than an all black surface. Crystals run to 4.5 cm. Notably, Charlie says this style of so-called schorl from Erongo has been characterized recently as the related species of tourmaline, foitite. Ex. Charlie Key Collection.