The mineral Malachite is a copper carbonate of common occurrence in copper bearing formations. It is well known for its vivid green colours and most commonly occurs in massive, amorphous, kidney-like structures, a form it owes to its deposition by hydrothermal precipitation from copper bearing fluids. Other modes of deposition may also occur like the rare silky fibrous habitat seen in this sample from the copper mining district in Katanga, Congo. Actual width is 140 mm.