Natural History - Large British Asteroceras Fossil Ammonite

A nickel iron (IAB) meteorite with irregular surfaces and a composition of 92.9% iron, 6.7% nickel. 81 grams, 40 mm



Discovered 1576 A.D., Chaco Province, Argentina. Ex Lincolnshire, UK, collection.

A crater field of roughly 26 craters was found in the vicinity of this crater, which is estimated to date to 4-5 thousand years BP. The age of the meteorite itself is thought to be c.4.5 billion years, formed as part of the development of this solar system. The largest two fragments, the 30.8 ton Gancedo and 28.8 ton El Chaco, are among the heaviest meteorite masses ever recovered on Earth. In 1576, the governor of a province in Northern Argentina commissioned the military to search for a large mass of iron, which it was believed local people claimed had fallen from the sky and which they used for their weapon production. The expedition discovered a large mass of metal which was assumed to be an iron mine and brought back a few samples, which were described as being of unusual purity. Following the legends, in 1774 Don Bartolomé Francisco de Maguna rediscovered the iron mass. He himself did not believe that the stone had fallen from the sky and assumed that it had formed by a volcanic eruption. However, he sent the samples to the Royal Society of London. In 1990 it became protected by law.

Comprising three composites of various sized ammonites with polished upper surface. 224 grams total, 81-82 mm



From Madagascar. Ex Lincolnshire, UK, collection.

The Cleoniceras sp. displaying iridescent surfaces. 890 grams total, 18.5 cm high including stand



From Madagascar.