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Mayo Belwa   contributed by jnmczurich, IMCA 2391   MetBul Link
 


Roll Overs:     Photo 1   Photo 2   Photo 3   Photo 4   Photo 5   Photo 6    

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View all entries for   Meteorite (3)   Contributor (65)


19.3 grams. 40 x 26 x 10 mm.   Aubrite

TKW 4.85 kg. Observed fall 3 August 1974, Adamawa district, Nigeria.

          WileyOnLine


Jürgen/jnmczurich writes:
Mayo Belwa, aubrite impact-melt breccia. Thick fragment slice, flat cut faces (pictures 1 and 2).

On one side (picture 2) of the shown Mayo Belwa sample are two deep cavities. The larger cavity is about 4.5 x 3.5 x 3 mm, the smaller cavity is about 2 x 1 x 1 mm. In both cavities are bundles of up to 1.5 mm long acicular grains of the amphibole fluor‐richterite to find (close-up pictures 3 to 5, about 8 x 6 mm). Picture 6 (about 8 x 6 mm) shows a metallic inclusion in the upper left part of the picture.

In my collection since 1994. Dealer trade.

Mayo Belwa is the first known aubrite impact melt breccia. It contains coarse enstatite grains exhibiting mosaic extinction; the enstatite grains are surrounded by a melt matrix composed of 3–16 μm‐size euhedral and subhedral enstatite grains embedded in sodic plagioclase. Numerous vugs, ranging from a few micrometers to a few millimeters in size, constitute ∼5 vol% of the meteorite. They occur nearly exclusively within the Mayo Belwa matrix; literature data show that some vugs are lined with bundles of acicular grains of the amphibole fluor‐richterite. This phase has been reported previously in only two other enstatite meteorites (Abee and St. Sauveur), both of which are EH‐chondrite impact melt breccias. It seems likely that in Mayo Belwa, volatiles were vaporized during an impact event and formed bubbles in the melt. As the melt solidified, the bubbles became cavities; plagioclase and fluor‐richterite crystallized at the margins of these cavities via reaction of the melt with the vapor.
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Photo 1

Photo 2

Photo 3

Photo 4

Photo 5

Photo 6

Found at the arrow (green or red) on the map below


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Tomorrow

NWA 4590
John Divelbiss

This Month

8 pictures in the Queue
John Cabassi
 6/11/2019 7:52:02 PM
Spectacular specimen, jaw dropping thanks Jurgen.
Andi Koppelt
 6/11/2019 12:35:29 PM
Marvellous rare piece with stunning needles. Never saw this before, thanks for posting, J*rgen.
Graham Ensor
 6/11/2019 6:05:52 AM
Thanks for showing this...wonderful specimen. One I was not aware of.
Mendy Ouzillou
 6/11/2019 3:45:10 AM
Absolutely fabulous piece on a rare Aubrite!
Bernd Pauli
 6/11/2019 3:44:18 AM
Astonishing that these delicate, filigree fluor-richterite needles survived the violent descent through the Earth's atmosphere intact!
 
 


Current server date and time: 9/17/2019 10:07:34 AM
Last revised 9/3/2019