Natural History - Very Large Australian Amethyst Crystal Specimens

A Charonosaurus sp. hadrosaur egg on a matrix retaining evidence of the original leathery surface. 3.9 kg, 16 cm wide



From a Cambridgeshire, UK, collection.

Dinosaur eggs are known from about 200 sites around the world, the majority in Asia and mostly in terrestrial (non-marine) rocks of Cretaceous Age. It may be that thick calcite eggshells evolved during the Cretaceous (145 to 65 million years ago). Most dinosaur eggs have one of two forms of eggshell that are distinct from the shells of related modern animal groups, such as turtles or birds; however, some eggs closely resemble the type of shells seen in present day ostrich eggs.

A group of six unpolished cut malachite sections. 1.05 kg total, 6-11.5 cm



D R of Congo. Mineral Imports, London, UK. Gregory, Bottley & Lloyd (Gregory's).

A pair of Knightia alta fossil fish in a matrix. 336 grams, 12.6 x 11 cm



From Wyoming, Green River Formation, U.S.A. Acquired during the 1980s. From the Pradi Collection, Boston, U.S.A.

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.