Natural History - Desert Rose Specimen Group [100]

Comprising brown and white scalenohedral calcite crystals on small pyrite crystals with acicular and druzy haematite; supplied in a labelled cardboard tray. 262 grams, 80 mm



From Huanuco, Peru. Ex Mineral Imports, London, UK. Gregory, Bottley & Lloyd (Gregory's).

The large slice with two polished faces showing some good detail. 1.11 kg, 19.2 cm



Acquired 1950s-1960s. From an old Bristol, UK, palaeontological collection.

The square sandstone matrix with two Knightia alta fossil fish specimens. 507 grams, 16 x 13 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.