Natural History - Historic 'Australia' Opal Specimen Group

The rectangular matrix containing four Knightia alta sp. fish. 955 grams, 24.2 cm



From the Green River Formation, Wyoming, USA. Ex 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.

The tabular crystals on quartz matrix. 75 grams, 50 mm



From Nenthead, Cumberland, 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.

Displaying hexagonal vanadinite crystals on cockscomb type barite, collection number 567, with an old Gregory, Bottley & Lloyd label. 54 grams, 48 mm



Acquired on the UK mineral and fossil market, since 1970. From the historic mineral collection of Richard Valentine Cain, London, UK, thence by descent. Accompanied by an original historic index file card.