Natural History - Polished Amethyst Crystal Pebble Group [100]

The large sandstone matrix with five Knightia alta specimens. 8.25 kg, 50.5 x 38 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.

All four specimens with dark purple crystals; supplied in labelled carboard trays. 303 grams total, 47-68 mm



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

Comprising two hollow wading bird bones. 13 grams total, 77-90 mm



From Rancho La Brea Formation, Maricopa Co., California, USA. Acquired 1950s-1960s. From an old Bristol, UK, palaeontological collection.