Calcite, calcium carbonate, CaCO3. Two more specimens of calcite from Creigiau quarry, South Wales. These and all other specimens in my collection were collected at one visit. The main picture is a cluster of several untidy twinned crystals. and in small pockets between them are small groups of small single bladed crystals with the appearance of flattened " rhombs ". The inset picture shows a single crystal which is not on the same scale, but which has been reduced in size to fit this illustration.