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21 - June - 2017
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contributed by Steve Brittenham, IMCA 2184
Photo Copyright (c) Steve Brittenham.
See Contributor comments. Lunar
NWA 4734 is an extensively shocked lunar mare basalt (an extrusive volcanic
rock that cooled from magma extruded onto the lunar surface). A very fresh
meteorite with a debated monzogabbro sub-classification, it has a mixture of
glossy black and duller black/brown fusion crust with an interior texture
described as shergottite-like by some and by others as eucritic. One of the
few unbrecciated lunar basalts, it is compositionally and texturally
identical with the Antarctic LaPaz Icefield meteorite basalts and is likely
launch paired from the same source crater. All have crystallization ages
around 3.1 billion years ago - younger than those associated with the Apollo
and Luna basalt examples - and while they also share very similar bulk
compositions, mineral compositions, textures, and age with NWA 032, the
latter is not felt to belong to this group.
NWA 4734 consists of several pieces, two totaling 477 grams that were
purchased by A. Habibi in October 2006, and several additional ones totaling
895 grams acquired by M. Oumama. Around that same time, an additional piece
was sold to E. Thompson and sent for separate classification. Then in
February 2016, a 350 gram piece now thought to be one of the original 895
gram group was purchased and given the name NWA 10597.
The piece shown in Photos 1 and 2 is from the first sets of recovered
stones. Because it's thin and irregular, it doesn't provide a particularly
good idea of the texture of this meteorite. Conversely the larger 35.9
gram, 50 x 44 x 13 mm piece in Photos 3 and 4 was cut from Thompson's stone
and gives a better idea of the meteorite's characteristic (in Photo 4, one
can also see where the classification piece was cut from the back side).
It's fun to pass this one around when my wife and I give meteorite talks at
the local schools - that way when the kids leave they can say they actually
touched a piece of the moon!
Click to view larger photos Photo 1 Photo 2 Photo 3 Photo 4
6/21/2017 1:37:47 PM
|lunar basalt two days in a row !! nice material too
6/21/2017 12:46:19 PM
|Hi Mike. Thanks for the nice comment. As an amateur in all of this, it's fun to research pieces I acquire and share what I learn. But things can change so fast that some of what I write about is either already wrong or becomes wrong shortly after! So hopefully it doesn*t seem like I*m professing to be an expert or anything * to the contrary, this is just a hobby of mine, and these write-ups are how I learn more about meteorites. But it*s nice to hear from people that are enjoying them. Again, thanks so much * it makes doing this that much more worthwhile!
6/21/2017 11:34:27 AM
|Steve, I really enjoy the background you provide with each MPOD you bring us. Both the provenance and the makeup of the subject stone is helpful in expanding my understanding of these cosmic missels.
6/21/2017 10:40:11 AM