It's been a while since I posted anything on meteorites. Today I'm getting my Meteorite Petting Zoo organized for a display at the Texas Astronomical Society's upcoming (Sept. 6th) observance of Astronomy Day.
Part of that process was deciding how best to display thin sections so the public can "see inside" a meteorite. The image below is the best of a series I made this morning using a newer, simpler technique which does not require a microscope.
This is what's called a petrographic thin section, which is essentially a paper-thin (30-micron) slice of rock mounted to a glass microscope slide. In this case, the rock is a piece of the meteorite named Vaca Muerta (Spanish for "dead cow"). It's a mesosiderite and the longest dimension of this particular slice is just under 20mm.
The colors are formed by cross-polarized light. Light from a flash unit passes through a polarizing filter beneath the thin section, through the crystals in the thin section, and then through another polarizing filter between the camera and the thin section. As you rotate one of the polarizers, you can position them so that no light at all passes through the polarizing filter "sandwich" except that which has been "modified" by passing through the crystals in the meteorite. I think the sandwich will make a nice display when laid out on a small light table (you can see the thin section exactly as it appears here except it will be a bit smaller.
The colors, and the way the light changes as it passes through a crystal, can tell you what mineral is present. The appearance of cracks and/or cleavage planes in the crystal can tell you something about whether the meteorite was remelted after initial formation, or whether it was shocked by an impact.
And, as well, the polarized light makes for simple, pretty pictures ...
Other examples, including macros as well as micrographs, are in my Meteorite Thin Sections set at Flickr!.
Update: I got the substage raise/lower mechanism on the Illumitran fixed, so it's much easier to do this now. Here's a new thin section (just got it this week) of the Allende meteorite:
Nice chondrules in there, some look like miniature "distant Earths" ...