This specimen features good sphalerite crystals from the Nanisivik Mine, along with some beautiful complex pyrite crystals. The sphalerite crystals are nestled into a protected area on the piece. The pyrite crystals are wonderful, and they are epitactic on pyrite-replaced marcasite. The crystals are in excellent condition, and the crystals around the periphery and underneath are incomplete where they were attached to adjoining crystals. A fine Nanisivik pyrite-sphalerite combination from the Steve Szilard collection.
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)