Medium Quartz Rock Crystal Specimen Collection [20]

Rectangular matrix with a Knightia alta specimen. 210 grams, 80 mm



From Wyoming (Green River Formation), USA. 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.

The upper part of a fossil Argochampsa krebsi crocodile skull on a sandy matrix wrapped in a plaster field jacket. 4.94 kg, 45 cm



From Morocco, North Africa. From a Cambridgeshire, UK, collection.

Argochampsa or 'Argo crocodile' is an extinct genus of eusuchian crocodylomorph, usually regarded as a gavialoid crocodilian, related to modern gharials. It lived in the Paleocene of Morocco. Described by Hua and Jouve in 2004, the type species is A. krebsi. Argochampsa had a long narrow snout, and apparently marine in its behaviour.

Comprising three polished slice showing banding and some with crystals; four dyed. 760 grams total, 10.6-13.4 cm



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