Diogenites belong to the evolved achondrite HED group that also includes howardites and eucrites. They are named after the Greek philosopher Diogenes of Apollonia, of the 5th century BCE, who was the first to suggest that meteorites come from outer space (a realization forgotten for over 2,000 years). They are Click on Term to Read More
A rock composed primarily of orthopyroxene. Non-terrestrial orthopyoxenites include diogenites and a single martian meteorite, ALH 84001, that was found in the Allan Hills region of Antarctica in 1984. ALH 84001 is a cumulate rock consisting of 97% coarse-grained, Mg-rich orthopyroxene, with small amounts of plagioclase, chromite, and carbonate. It Click on Term to Read More
(≥90 vol% Orthorhombic, low-Ca pyroxene common in chondrites. Its compositional range runs from all Mg-rich enstatite, MgSiO3 to Fe-rich ferrosilite, FeSiO3. These end-members form an almost complete solid solution where Mg2+ substitutes for Fe2+ up to about 90 mol. % and Ca substitutes no more than ~5 mol. % (higher Ca2+ contents occur Click on Term to Read More)
click on photo for a magnified view Fell July 6, 1924
40° 21′ N., 104° 54′ W. At 4:20 P.M. in Weld County, Colorado, four explosions were heard followed by the Meteorite seen to fall. Such meteorites are usually collected soon after falling and are not affected by terrestrial weathering (Weathering = 0). Beginning in 2014 (date needs confirmation), the NomComm adopted the use of the terms "probable fall" and "confirmed fall" to provide better insight into the meteorite's history. If Click on Term to Read More of 28 stones ranging in weight from a few grams to 23.5 kg. A crowd of mourners attending the burial service for John Moore Sr. at the Elwell Cemetery, two miles west of Johnstown, witnessed the fall. A few of the attendees walked across the road to a field and proceeded to dig up a 6.8 kg stone, now on display in the Denver Museum of Natural History. The fragment size distribution of this fall is reversed from the usual, with the larger fragments being found at the beginning of the strewnfield ellipse rather than at the end. This can be explained by the breakup of a large fragment late in its flight. The total collected weight of Johnstown is about 40.3 kg.
click on image for a magnified view
Photo courtesy of Peter Marmet
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