Natural History - Historic Arsenopyrite Crystal Formation

Cut and polished from a single fossiliferous block and each side set with a large Goniatite sp. specimen. 3.4 kg total, 15.3 cm high each



From a Cambridgeshire, UK, collection.

The Knightia alta specimen on a sandstone matrix with remains of another fish. 1 kg, 17.5 x 14.5 cm



From a Lincolnshire, UK, collection.

In southwest Wyoming (and parts of Colorado and Utah) in the Green River Formation are found some of the world's most outstanding specimens of fossil fish. The Green River system was composed of three lakes: Lake Ulinta, Lake Gosiute and Fossil Lake. These Eocene lakes lay in a series of intermountain basins formed by geological events that uplifted the Rocky Mountains during the early Tertiary time. The climate was much different from the desert-like climate of this area today. Both the fauna (crocodiles, alligators, boa constrictors and some subtropical fish families) and the flora (such as large palm trees) indicate a climate much like that found along the Gulf Coast today. Large amounts of ash found in the sediments indicate that volcanoes were particularly active at this time.

Comprising light blue tabular crystals forming an almost perfect triangle. 117 grams, 66 mm



From Nchanga, Zambia. Collected in person in 1974. From the private mineral collection of Stephen Atkinson, Harpenden, UK. Accompanied by a copy of a letter from the vendor giving details of him collecting these minerals throughout his life.