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Magnified Martian 'Glass'

Martian Glass? Well, sort of! These are images of the Martian Meteorite NWA 2986. It is a Shergottite (type of Martian meteorite). The shots are of mineral grains floating in window clear Martian glass. They are viewed at a magnification of 160X in cross polarized light with the use of a 1/4 wave filter plate used to draw out color in the mineral grains while keeping the glass relatively color free. The meteorite is mounted on a glass slide and polished to 30 microns thick (it is called a thin section). This allows light to pass through the stone.

I sent some shots to Dr. Tony Irving of the University of Washington and he was so cool! He took the time to provide an explanation of this glass.

This is what he wrote:

"The clear glass is maskelynite, which is produced by shock transformation of plagioclase (labradorite) during ejection of most Martian meteorites (except nakhlites). It's called a diaplectic glass, and is formed not by melting but by shock distortion of the feldspar crystal structure to the point where it becomes amorphous and amazingly clear (limpid like distilled water). Thus it will not have any vesicles (just tiny inclusions of pigeonite, phosphates, oxides, etc. that were originally inside the plagioclase on Mars). However, elsewhere in the thin section there could be some cross-cutting dark, glassy shock veins that do contain vesicles (of trapped Martian air, which in other shergottites is the proof of Martian origin for all such rocks)."

--Tom Phillips