Natural History - Australian Boulder Opal Specimen

Comprising natural rough pebbles in a range of sizes. 438 grams total, 11-23 mm



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

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.

Comprising white and blue radial aggregates. 129 grams, 12.2 cm



From Cornwall, UK. Collected in person in 1965. 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.