Natural History - Large Brown Calcite Specimen Group [10]

A set of four polished coasters with cork backing, showing attractive layering. 560 grams total, 94 mm each



From a Cambridgeshire, UK, collection.

Greyish, imperfect calcite crystals on a bed of small iridescent pyrite crystals, collection number 517. 698 grams, 10.8 cm



Acquired on the UK mineral and fossil market, since 1970. From the historic mineral collection of Richard Valentine Cain, London, UK, thence by descent. Accompanied by an original historic index file card.

A cut slice of scarce achondrite from the diogenite group recorded as: Northwest Africa 5480; displayed in a Swiss membrane box. 11.7 grams, 48 mm (58 grams total, 99 x 75 including case)



From the Sahara, N.W. Africa. Ex Hupe collection, U.S.A. From a Leicestershire, UK, collection.

The total known mass of the meteorite found in Mali was 4.91 kg. Mineralogically, the diogenites are primarily composed of magnesium-rich orthopyroxene, with minor amounts of plagioclase and olivine. The pyroxenes are usually coarse-grained, suggesting a cumulate origin for the diogenites in magma chambers within the deeper regions of Vesta's crust. The achondrites of this group are named after a 5th century B.C. Greek philosopher Diogenes of Apollonia, who was the first to suggest that meteorites originate from outer space.