This specimen exhibits two types of pseudomorphs. The base is composed of small Chalcopyrite crystals which formed over Galena crystals. The Galena crystals are no longer extant leaving a cast. Some of the Calcite has partially altered to Malachite due to substitution of calcium with copper with the Chalcopyrite being the probable source of the copper.
Flaws: Two of the side faces of the largest crystal show extensive contact surfaces (see the 4th picture).