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Thin section.   Achondrite-ung

TKW 12.4 kg. Fall not observed. Purchased 2021. Found by meteorite hunters in Western Sahara.


 

Steve writes:

Today in the U.S., we celebrate Independence Day with barbeques and fireworks. So to honor this holiday, I thought I’d offer xpol and white light thin section images of Al Bir Lahlou 001 in this somewhat tongue-in-cheek post.

Unfortunately, I don’t have any actual pieces of this meteorite to go with my thin section, but I understand the parent material has vivid green olivine liberally interspersed within a cream-colored plagioclase matrix. Described in the MetBul as a norite, its pyroxene composition is similar to diogenites, but its plagioclase abundance is too high for that classification, and its anorthite abundance is greater than in any HED meteorites. Hence, it’s classified as an ungrouped achondrite.

My gigapixel xpol and white light images, respectively, of this thin section can be seen here: Larger images can be seen on gigapan:

   xpol thin section

   white light thin section, improved exposure

For those new to Gigapan, click on the diagonal arrows at the upper right of the image to go full screen, then use your mouse to pan around and its scroll wheel to zoom in and out.

Descriptions of the photos are:

Photo 1: low resolution single complete xpol image of the slide

Photo 2: corresponding low resolution complete white light image

Photo 3: animated GIF overlaying Photos 1 and 2 for direct comparison

Photos 4 through 6: examples of radial plagioclase grains (roughly centered in each image)

In contrast to the pyroxene grains, the intermingled plagioclase ones in Photo 3 are virtually transparent in white light. Photos 4 through 6 were included because I’ve not seen radial plagioclase grains like these in my other thin sections.

Photo 7, an animated GIF, is included for those with pareidolia (or just thought that the right side of the white light thin section image looked a bit like a dog’s head).

And finally, the reason I chose this meteorite thin section for today’s post: since the radial grains looked a little like fireworks, Video 8 is my crude and corny attempt to honor this day. My apologies for those cringing at the unscientific display of meteorite characteristics!