Meteorite NWA 13302 - Mesosiderite type A3 with a Poikioblastic texture

Description

NWA 13302
NWA 13302
Found Sahara, 2019
Stony-Iron
Mesosiderite type A3
Specimen is a 2.78g slice
Only 5 mesosiderite A3 are referenced on the Meteoritical Bulletin
Sample is a breccia composed of : 0.5-10mm clasts of normally-zoned, anhedral orthopyroxene (Fs18-32Wo0.9-2.4) and 8 vol% un-zoned, anhedral olivine (Fa34.72-37.49) set within a matrix of poikiloblastic, exsolved Opx (Fs34.5+/-1.4Wo2.4+/-0.23) (all pyx 47 vol%) with an avg. grainsize of 523μm, 257μm anhedral plagioclase (22 vol%), and 18vol% cm-sized rounded nuggets and irregular-shaped intergrowths of FeNi metal. Matrix pyroxenes show lamellar to blebby exsolution. Olivine shows reaction coronas. Orthopyroxene makes up 63% of silicates and plagioclase makes up 31% of silicates. Additional minerals are: kamacite, taenite, lath-shaped Si polymorph (5 vol%), apatite, troilite, FeNi metal, chromite, trace ilmenite.
FeNi metal lacks oxidation rims. Sample shows limited weathering.
Sample is type A based on modal abundance of plagioclase and orthopyroxene.
Sample is type 3 based on poikioblastic texture with interlocking grain boundaries and inverted, exsolved pyroxenes.
Northwest Africa 13302
Basic information
Name:
Northwest Africa 13302
This is an OFFICIAL meteorite name.
Abbreviation:
NWA 13302
Observed fall:
No
Year found:
2020
Country:
Morocco
Mass:
403 g
Classification
history:
Recommended:
Mesosiderite-A3
This is 1 of 5 approved meteorites classified as Mesosiderite-A3.
[show all]
Comments:
Approved 31 May 2020
Writeup
Writeup from MB 109:
Northwest Africa 13302
(NWA 13302)
Morocco
Purchased: 2020
Classification: Mesosiderite- A3
History
: The 402.8 g sample was found in Morocco. Fabien
Kuntz
purchased the sample in Zagora, Morocco, in February 2020.
Physical characteristics
: Sample is irregular in shape and has a reddish-brown exterior with visible flakes of metal protruding through the surface. The cut face shows a metal-rich interior with angular clasts of pyroxene.
Petrography
: Sample is a breccia composed of: 0.5-10 mm clasts of normally zoned, anhedral orthopyroxene (Fs
18-32
Wo
0.9-2.4
) and 8 vol% unzoned, anhedral olivine (Fa
34.72-37.49
) set within a matrix of: 523 μm (avg. grain size) poikiloblastic, exsolved Opx (Fs
34.5±1.4
Wo
2.4±0.23
) (all pyx 47 vol%); 257 μm anhedral plagioclase (22 vol%), and 18 vol% cm-sized rounded nuggets and irregularly shaped intergrowths of FeNi metal. Matrix pyroxenes show lamellar to blebby exsolution. Olivine shows reaction coronas. Orthopyroxene makes up 63% of silicates and plagioclase makes up 31% of silicates. Additional minerals are: kamacite, taenite, lath-shaped Si polymorph (5 vol%), apatite, troilite, FeNi metal, chromite, trace ilmenite.
Geochemistry
: (A. Love,
App
) Olivine, Fa
36.1±1.4
(Fa
34.7-37.5
), Fe/Mn=36.8-36.8, n=2); low-Ca pyroxene, Fs
30.6±4.5
Wo
2.0±0.5
(Fs
23.0-35.6
Wo
1.4-2.7
,Fe/Mn=25.3±2.6, n=8); high-Ca pyroxene (Fs
17.2
Wo
38.8
, n=1); plagioclase (An
93.0±1.0
Or
0.1±0.0
, n=8).
Classification
: Mesosiderite (class A3) Sample is type A based on modal abundance of plagioclase and orthopyroxene. Sample is type 3 based on poikioblastic texture with interlocking grain boundaries and inverted, exsolved pyroxenes.
Specimens
: Fabien
Kuntz
holds the main mass. An endcut and part slice weighing 33.9 0g and a polished mount are on deposit at
App
.
Data from:
MB109
Table 0
Line 0:
Place of purchase:
Zagora, Morocco
Date:
P 2020
Mass (g):
402.8
Pieces:
1
Class:
Mesosiderite-A3
Shock stage:
low
Weathering grade:
low
Fayalite (mol%):
36.1±1.4
Ferrosilite (mol%):
30.6±4.5; 17.2
Wollastonite (mol%):
2.0±0.5; 38.8
Magnetic suscept.:
5.72
Classifier:
A. Love, App
Type spec mass (g):
33.9
Type spec location:
App
Main mass:
Fabien Kuntz
Comments:
Submitted by Anthony Love
Institutions
and collections
App
: Department of Geology, 572 Rivers St., Appalachian State University, Boone, NC 28608, United States (institutional address; updated 7 Mar 2013)
Kuntz
: Fabien Kuntz, France;
Website
(private address)
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