Martian Meteorite Thin Sections
The following photos are with a microscope and a special poloraizing filter that is under development.
The images were taken by placing a quality digital camera to the eyepiece of a standard microscope fitted with the polarizing device. The photos are a bit fuzzy ,but as actually seen through the eyepiece the images are very clear and spectacular.
To achieve such, the specimen in question must be prepared in such a way that light can shine through it. A thin section is made by cutting very precisely one face, attaching it to a glass slide then grinding down the rest so that a slice only 30 microns thin is the result-- thinner than a human hair.
The structures seen are the result of extreme shock caused by ejection from the surface of Mars by asteroid impactors. In the process of achieving escape velocity, certain minerals, particularly plagioclase is converted to glass. Under cross polarization this glass, Maskelynite, appears as the black between the colorful mineral grains, and the shocked but otherwise unaltered crystals appear in multicolor. Maskelynite is clear under normal light and contains traces of Martian atmosphere and is one of the hallmarks of Martian meteorites. The colors in the other minerals reveal the history of the specimen before it was ejected from Mars. Such minerals may also contain structures that some believe indicate life on Mars. They also have traces of nuclides that reveal cosmic ray exposure. And from this the space history of the Martian rocks can be determined as they traveled between Mars and the Earth. Most orbited the Sun for about 10 million years before being captured by the Earth to fall to the ground as meteorites.
Chassigny, France Fell Oct 3, 1815
Petrologic slide with speck of meteorite at its center. Scale is in millimeters.
Scale of each each photomicrograph is about 1 mm.
Cassigny Martian dunite, picture #1
Zagami, Nigeria; Fell Oct.. 3. 1962
Petrologic slide with 10 mm x 8 mm thin section.