Heterogenite with Malachite

This showy cabinet specimen of beautifully crystallised Heterogenite and Malachite is from the L'Etoile du Congo mine at Lubumbashi within the Katanga Copper Crescent of the Democratic Republic of Congo, perhaps better known as the Star of the Congo mine. Heterogenite, a tri-valent cobalt oxyhydroxide, forms aesthetic drusy rafts of 1 to 2 mm diameter botryoidal black crystals, all with a bright lustre and often with a bluish cast, the colour of Clinoclase (please note: there is no Clinoclase on the specimen!). In scattered patches overgrowing the Heterogenite, deep emerald green Malachite forms micro acicular crystals whose velvet-like texture and matt lustre contrast superbly against the reflective dark Heterogenite. The banded matrix is shot through with diverging thin veinlets of turquoise blue Chrysocolla. A beautiful specimen indeed.