Natural History - Cut and Polished Thunder Egg Half

A fossil Diplomystus sp. fish in a matrix. 500 grams, 16.5 x 11.7 cm



From the Green River Formation, Lincoln County, Wyoming, U.S.A. From an old Lincoln, UK, collection.

Seasonally, some 56 million years ago, in the Green River Region of Wyoming, torrential rains fell on the mountains. The rain flowed down the mountain sides, forming wide shallow lakes in the valley below. During the dry season, these lakes evaporated (similar to certain parts of Africa today). Millions of fish died in this short period of time. This climatic cycle happened over a 20-thousand-year period. Layer upon layer of mud was deposited over these years, entombing huge numbers of fish. At a much later date volcanic activity uplifted this area to expose their fossils.

A polished fossil Cymatoceras sakalavus nautilus. 215 grams, 76 mm



From the jungles of Mahajanga on the North West coast of Madagascar. From an old Oxfordshire, UK, fossil and mineral collection.

A group of 20 crystalline labradorite specimens of dark colour, with a waxy lustre; a calcium-enriched feldspar mineral first identified in Labrador, Canada, which can display an iridescent effect. 2.79 kg total, 4.6-10.6 cm



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