Natural History - Large Brown Calcite Mineral Specimens [12]

Comprising lacquered porphyry slice of irregular shape, cut and polished on one side, probably recycled material mined in ancient Roman times between the 1st and 5th century A.D. 917 grams, 28 cm



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

Mons Porphyrites (today Jabal Abu Dukhkhan) is the mountainous site of a group of ancient quarries in the Red Sea Hills of the inhospitable eastern desert in Egypt, a five day trip from the Nile during Roman times. They were discovered by Caius Cominus Leugas in 18 A.D., and during the Roman Empire the mines officially belonged to the emperor and were the only known source of the Imperial Porphyry, Mons Porphyrites. This dark purple stone was associated with royalty and used for prestigious sculpture and architecture. The location of the mines was lost some time in the 5th century, and rediscovered in the early 19th century. Excavations in the area have revealed the well-preserved quarries and the dwelling places of the quarry men, and also thousands of ostraca have been discovered containing messages that provide details of how the quarrying took place, and of how the highly skilled quarrymen ordered their food.

A quantity of ammonite specimens on an irregular matrix, possibly Cymbites. 916 grams, 18 cm



From Whitby, UK. From a Lincolnshire, UK, collection.

Diplomystus sp. specimen on a matrix. 267 grams, 10 x 15 cm



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.