Natural History - Fossil Double Perisphinctes Ammonite

A polished and opened nodule with a Dactylioceras commune sp. specimen. 223 grams, 69 mm



From a Cambridgeshire, UK, collection. Property of a Cambridgeshire, UK, gentleman.

Comprising a section of nickel-iron meteorite (IAB) set with a suspension loop and suspended from a cord necklace; supplied in a gift box. 27 grams total, meteorite: 30 mm



From a Lincolnshire, UK, collection. Property of a Cambridgeshire, UK, gentleman.

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 the 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.

A highly polished rectangular slice of the Seymchan meteorite with an exceptional number of transparent olivine inclusions, repaired. 62.4 grams, 12 cm



From the private collection of a London gentleman, from his grandfather's collection formed before the early 1970s.

The main mass of 272.3 kilograms was found during a survey in June 1967 by geologist F. A. Mednikov. The mass was a triangular-shaped thumb printed meteorite lying among the stones of the brook bed. A second specimen of 51 kilograms was found with a mine detector at a distance of 20 meters from the first in October 1967 by I. H. Markov. During a new expedition in 2004, Dmitri Kachalin recovered about 50 kilograms of new material. Remarkably, about 20% of the new specimens were found to contain olivine crystals, and so revealed the silicate nature of the meteorite. The pallasitic structure was not previously discovered during studies on small metal-only sections of the original mass. The distortion of the Widmanstatten patterns is interpreted as shearing of the superheated meteorite as it broke up in the Earth's atmosphere.