An achondrite is a type of stony meteorite whose precursor was of chondritic origin and experienced metamorphic and igneous processes. They have a planetary or differentiated asteroidal origin where the chondritic parent body reached a sufficient size that through heating due to radioactive decay of 26Al (aluminum isotope) and gravitational Click on Term to Read More, Modifying term used to describe meteorites that are mineralogically and/or chemically unique and defy classification into the group or sub-group they most closely resemble. Some examples include Ungrouped Achondrite (achondrite-ung), Ungrouped Chondrite (chondrite-ung), Ungrouped Iron (iron-ung), and Ungrouped Carbonaceous (C-ung). Click on Term to Read More
click on photos for a magnified view Purchased 2016
no coordinates recorded A relatively fresh Work in progress. A solid natural object reaching a planet’s surface from interplanetary space. Solid portion of a meteoroid that survives its fall to Earth, or some other body. Meteorites are classified as stony meteorites, iron meteorites, and stony-iron meteorites. These groups are further divided according to their mineralogy and Click on Term to Read More weighing 36.67 g was found in Northwest Africa and subsequently purchased by J. Higgins in October 2016 from a dealer in Nouakchott, Mauritania. A sample was analyzed at the University of Washington in Seattle (A. Irving and S. Kuehner) and NWA 11187 was classified as an ungrouped achondrite that has mineralogical and geochemical affinities to the ureilite group.
click on image for a magnified view Diagram credit: Li et al., GCA, vol. 242, p. 92 (2018)
‘Evidence for a Multilayered Internal Structure of the Chondritic Acapulcoite–Lodranite Parent Asteroid’
(https://doi.org/10.1016/j.gca.2018.09.004) Northwest Africa 11187 shows evidence for low shock and a low degree of terrestrial weathering. The Largest fragment of a meteorite, typically at the time of recovery. Meteorites are commonly cut, sliced or sometimes broken thus reducing the size of the main mass and the resulting largest specimen is called the "largest known mass". Click on Term to Read More of this meteorite resides in the Royal Ontario Museum. The specimen of NWA 11187 shown above is a 0.25 g partial slice that was taken from the ~1 g slice shown below.
mouseover for reverse view Photos courtesy of John Higgins—Outer Space Rocks
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