Wandering Star Meteorites
Angrite Meteorites
Thin section from testing
The angrite class are basaltic rocks with cumulate textures and are made up primarily of fassaitic pyroxene, anorthitic plagioclase and olivine. One of the unusual things about the chemical composition is the aluminum, titanium and calcium found within the meteorite. The mix is unlike any other meteorite type known.
Angrites are the oldest igneous rock we know of, showing crystallization ages of 4.55 billion years old. This data tells us the formation happened very early on while the solar system was forming.
From the study of formation of angrites, we have learned that a rapid melting and cooling event on the parent body must have occurred following a decompression phase of enormous proportions. They usually have some porous areas and also vesicles that are remnants of gas formed bubbles that were created prior to the crystallization of the rock.
One of the most accepted and peer reviewed studies present the theory that angrites are ejecta from the planet Mercury. Recent findings from the last couple years have shown high enough amounts of iron on Mercury that seem to support this (The main point against the parent body being Mercury was a question of iron content on the planet)
Once the Messenger spacecraft begins to study Mercury in 2011, it may be able to answer many questions about the origin of this very interesting meteorite.
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NWA 6291 - 2.49 gram slice
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Here are some links to PDF files that contain a wealth of information on studies that have been done on angrites:
http://www.lpi.usra.edu/meetings/lpsc2010/pdf/2680.pdf
http://www.lpi.usra.edu/meetings/lpsc2009/pdf/1345.pdf
http://www.lpi.usra.edu/meetings/lpsc2009/pdf/2403.pdf
http://www.lpi.usra.edu/meetings/LPSC99/pdf/1953.pdf
http://www.lpi.usra.edu/meetings/lpsc2009/pdf/1381.pdf
http://www.lpi.usra.edu/meetings/lpsc2009/pdf/2453.pdf
http://www.lpi.usra.edu/meetings/lpsc2008/pdf/1936.pdf
http://www.lpi.usra.edu/meetings/lpsc2008/pdf/2143.pdf
http://www.lpi.usra.edu/meetings/lpsc2007/pdf/1423.pdf
http://www.lpi.usra.edu/meetings/lpsc2007/pdf/1612.pdf
http://www.lpi.usra.edu/meetings/lpsc2007/pdf/1522.pdf
http://www.lpi.usra.edu/meetings/lpsc2007/pdf/1203.pdf
http://www.lpi.usra.edu/meetings/metchron2007/pdf/4061.pdf
http://www.lpi.usra.edu/meetings/lpsc2010/pdf/2680.pdf
http://www.lpi.usra.edu/meetings/lpsc2009/pdf/1345.pdf
http://www.lpi.usra.edu/meetings/lpsc2009/pdf/2403.pdf
http://www.lpi.usra.edu/meetings/LPSC99/pdf/1953.pdf
http://www.lpi.usra.edu/meetings/lpsc2009/pdf/1381.pdf
http://www.lpi.usra.edu/meetings/lpsc2009/pdf/2453.pdf
http://www.lpi.usra.edu/meetings/lpsc2008/pdf/1936.pdf
http://www.lpi.usra.edu/meetings/lpsc2008/pdf/2143.pdf
http://www.lpi.usra.edu/meetings/lpsc2007/pdf/1423.pdf
http://www.lpi.usra.edu/meetings/lpsc2007/pdf/1612.pdf
http://www.lpi.usra.edu/meetings/lpsc2007/pdf/1522.pdf
http://www.lpi.usra.edu/meetings/lpsc2007/pdf/1203.pdf
http://www.lpi.usra.edu/meetings/metchron2007/pdf/4061.pdf
