An Article In Meteorite-Times Magazine
by Tom Phillips
NWA 2977 Lunar
Jim Strope gets the credit on this batch of micrographs. About a year ago I had the opportunity to examine some of his other planetary thin sections and I mentioned to him that I sure would like to get a look at that exciting Lunar NWA 2977. He immediately said he would provide the necessary material for a thin section. Jeff Hodges arranged the manufacture of the thin to his new 1/4 micron double polish standards.
The thin is beautiful! Thanks Jim and Jeff!
The following is a partial description taken from Jim's web site catchafallingstar.com .
NWA 2977 is a lunar gabbro meteorite that contains two pyroxenes, olivine, plagioclase shocked to maskelynite, K, Ba feldspar, and various Cr, Fe, Ti oxides. This cumulate lunar rock (cumulate = accumulation of crystals by gravity settling in a magma) probably originated in the lunar highlands environment as a thick lava flow or as a shallow intrusive into the highlands crust. After formation, the gabbro was moderately shocked by hypervelocity impact.
Check out http://www.catchafallingstar.com/nwa2977.htm for much more information and great photos. I think he even still has some for sale!!!
You will not believe the microscopic beauty in this material.
This first set is taken at a magnification of 160X in cross polarized transmitted light with a 1/4 wave plate. I couldn't stop looking at this slide!
This set is taking it up to 400X using the same techniques as the 160X set.
I figured I would show the objectives I am using on these next two sets. I occasionally get questions (which I look forward to) about what equipment I am using.
This set is taken at a magnification of 760X using an aus Jena 40X Apochromat dry (no immersion oil) objective. It has an adjustable aperture correction for the thickness of the thin section cover slip. It is a new find for me and I wanted to show it off! I was very happy with the results.
1600X! This is the objective I used for the next set. I show this objective because of the high magnification, especially when you take into account it is reflected cross polarized light. This one is an aus Jena 100X Apochromat oil immersion lens designed for incident light work.
Look at those opaque compounds. Those would be black in transmitted light.
What's this? A speck of iron? Is that a pattern in it?
I use a Glan/Thompson style polarizer with nearly total extinction. It will draw out the crystal structure differences in make up or orientation and display them as well as an acid etch. (Even better because it is effective on a much smaller scale)
The first speck got me looking and check out what I found! A fairly nice sized piece of iron in a Lunar! The best part is this piece has a well defined pattern. I'm not saying this is Widmanstatten Pattern but I like to think the processes are the same. Notice how the dark and light sections change in rotation. This would likely be meteoric iron! A piece of a meteorite on the moon!
I don't know if this is the first finding of a mineral migration pattern in a Lunar iron fleck but is certainly the first for me!
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