This splendid specimen from the St. Agnes mining district of Cornwall is of museum standard and of a quality very rarely seen on the open market for collectors. An intergrown group of large, heavily striated, brassy tetragonal Chalcopyrite crystals perch on top of a Quartz matrix, itself covered with narrow, tapered colourless Quartz crystals to 2 cm, many of which have a snow-white matt powdery-like coating. The two largest Chalcopyrite crystals measure 3.5 cm on edge and have a fabulous patina of tarnished black and brassy-golden Chalcopyrite, so typical of classic specimens from this locality. The St. Agnes granite boss is classified as a Type 3 megacryst granite and is an isolated small area of complex mineralization on the coast of Cornwall, due north of Redruth. This specimen has no damage and the combination of such magnificent Chalcopyrite crystals against the matt white Quartz is superb.
