Beautiful complex pyrite crystals from Nanisivik. These crystals combine cube, octahedron, dodecahedron and trapezohedron forms – they have a LOT of faces! (Great illustrations of this in the article referred to below.) The crystals are oriented in the manner of many Nanisivik pyrite crystals – they are epitactic on pyritized marcasite (so they are in aggregates as if overgrowing straight, underlying marcasite blades). In very good good condition – the central pyrite crystals are excellent and look superb from the optimal viewing angle, and around the periphery there are incomplete crystal faces and a couple of contacts. From the Steve Szilard collection, a classic from the Nanisivik Mine – this complex crystallization is what made Nanisivik world famous among collectors.
About the Nanisivik Mine
The Nanisivik Mine is in the far north, near the northernmost edge of Baffin Island in the Canadian Arctic, at 73 degrees north latitude. It operated from 1976 to 2002, and was an important producer of exquisite pyrite specimens, along with beautiful specimens of other sulphide minerals, and quartz, dolomite and calcite. The mine’s location made for some extreme conditions. Weeks of total darkness in the winter could see temperatures down to -50C (-58F). In the summer, while the outdoor temperatures could be +10C (50F), the temperature in the mine was -15C (5F) thanks to a 500 metre-thick permafrost layer. The vugs containing crystals were ice-filled, and collecting involved the use of ice picks. This was challenging, but at least the ice protected the crystals during collecting. Specimens were removed with the ice remaining attached, and then melted gradually at the surface to expose the crystals. Collecting was usually impossible during summer months because the underground walls would become coated with thick layers of frost and ice (like the inside of a freezer), obscuring any chance of seeing crystal vugs. Today, the mine is most broadly remembered for the spectacular complex pyrite crystals it produced.
There is a great article on the locality:
Gait, R.I, G.W. Robinson, K. Bailey and D. Dumka, 1990. Minerals of the Nanisivik Mine, Baffin Island, Northwest Territories.* Mineralogical Record 21: 515-534.
(* this region of Nunavut was formerly part of the Northwest Territories)