Heterogenite on Chrysocolla, Katanga, Democratic Republic of Congo

Heterogenite is cobalt-bearing mineral with very odd chemistry. According to Mindat.org, heterogenite is traditionally referred to a cobalt oxy-hydroxide CoO(OH), which is uncommon enough. However, recent analytical work suggests it is more complicated and I refer those interested to review the Mindat discussion. The Katanga area in the DRC is a large cobalt and copper producing region yielding many attractive minerals. The specimen shown here is an excellent combination piece of heterogenite (botryoidal black crystals) on blue-green chrysocolla. Malachite is present as well. Often, heterogenite is dull but this example displays nice luster and sparkles even in low light. This is a hefty, cabinet-sized specimen, originally from the Garry Kolodinsky collection. The older label states this specimen is from "Katanga" but this province was split into four new areas in 2015. From Katanga, Democratic Republic of Congo. Dimensions: 3 cm x 10 cm x 12 cm