Well developed cubic Fluorite crystals on Siderite with Chalcopyrite, from the Carn Brea Mine, Illogan, Cornwall. Crystals of Fluorite measure to 1cm are purple , with colourless zones, translucent-opaque. Lustrous brassy yellow sphenoidal crystals of Chalcopyrite, measuring to 5mm, are scattered over the tan-biscuit coloured inter grown lenticular Siderite crystals, on a matrix of banded Quartz-Chlorite.