NWA 13297 LL3 Primitive Chondrite Meteorite 2.7 gram tablet

Description

NORTHWEST AFRICA 13297
LL3 PRIMITIVE CHONDRITE METEORITE
2.7 GRAM TABLET
Physical Characteristics: Most samples are flat and tabular in shape. One sample is irregular
shaped with a dark brown weathered exterior. The cut face of the irregular sample shows a
fresh, un-weathered interior composed of abundant chondrules surrounded by fine-grained
sulfide rims. FeNi grains occur within the interiors of chondrules. The unweathered interior is
surrounded by a well-developed weathering rind. Material in the weathering rind is identical to
tabular samples.
Petrography: Description and classification (A.Love, App) Sample has a chondritic texture
composed of distinct, close-packed chondrules with an average apparent diameter of 763?m
(n=77) set within an opaque matrix. Chondrules are surrounded by fine-grained rims of sulfide
and have mesostasis commonly composed of isotropic glass and devitrified glass (dominant).
Clinoenstatite is the dominant pyroxene phase.
Shock: Olivines show undulatory extinction and contain both irregular and planar fractures.
Sample contains a prominent set of subparallel fractures that occur parallel to sheet structure
of samples. Troilite is polycrystalline. The sample shows pervasive small melt pockets
containing FeS melt droplets. Olivine shows yellowing (from shock).
Weathering: Sample is stained with FeOH minerals. All FeNi metal has been altered and troilite
is partially to weakly altered. Sample contains calcite within sets of subparallel fractures that
may influence morphology of samples. The sample with the weathering rind shows concentric
cracks surrounding the unweathered portion. The tabular samples may represent spalled pieces
from spheroidal weathering of the main mass.
Magnetic Susceptibility: Quadruplicate measurements of 5 stones produced log c x 10-9 m3
/kg= 4.33. A 6th stone containing an un-weathered interior gave a log c x 10-9 m3
/kg=4.74. These values fits within the range for LL chondrites (Rochette et al., 2003).
Cathodoluminescence Microscopy: CL was observed using the CL Olympus BX-51 with a
Reliotron CL control and stage housed within the Department of Geology at Appalachian State
University. Observations were made at 8 KV.
Chondrules commonly show show bright and dark red CL. Yellow mesostasis is common and
blue mesostasis is present. Matrix CL is low. CL chondrule types (after DeHart et al., 1992) A1-
15%; A2-30%; A3-6%; A4-1%; A5-22%; B1-17%; B2-3%; B3-5%.
Geochemistry: (A. Love, App) Geochemistry was measured using the JEOL ITS300 SEM with
EDAX EDS in the Dewel Microscopy Lab at Appalachian State University. An accelerating voltage
of 20kV was used to analyze 3 spots per grain. Olivine and pyroxene are unequilibrated.
Olivine (Fa16.75+/-9.74 (Fa0.59-27.06), Fe/Mn=36.62+/-11.81, n=12. Cr2O3 in type II
chondrules has an average of 0.22 +/-0.09 (, n=10); low Ca-pyroxene (Fs12.91+/-9.55Wo0.88+/-
0.63 (Fs1.73-31.48Wo0.25-2.50), n=10.
Fig. 7 Mean Cr2O3 concentration in Ferroan olivines (>Fa2) Vs. standard deviation of these
measurements (after Grossman and Brearly, 2005). Sample is marked by the yellow star.
Classification: Ordinary chondrite (LL3 C-S2 W1) Based on chondrule size and magnetic
susceptibility this sample is an LL chondrite. Estimated subtype for this sample is between 3.15
and 3.2 based on unequilibrated compositions, presence of isotropic glass mesostasis (<3.3),
yellow CL in chondrule mesostasis (3.1-3.2) and presence of red luminescence in chondrule
olivine <3.5) and low CL of matrix (>3.1).
Specimens: John Higgins and Carlos Munoz hold the main masses of this meteorite. Many
spalled tabular fragments, an endcut and many tabular fragments weighing a total of 130g are
and a polished thin section are on deposit at App.
References:
DeHart, J. M., Lofgren, G.E., Jie, L., Benoit, P.H. and Sears, D.W., 1992. Chemical and physical
studies of chondrites: X. Cathodoluminescence and phase composition studies of
metamorphism and nebular processes in chondrules of type 3 ordinary chondrites. Geochemica
et Cosmochemica Acta Vol. 56, pp. 3791-3807.
Grossman, J. and Brearly, A., 2005. The Onset of Metamorphism in Ordinary and Carbonaceous
Chondrites. MAPS 40, 1. pp.87-122.
Rochette, P., Sagnotti, L., Bourot-Denise, M., Consolmagno, G., Folco, L., Gattacceca, Osete,M.
L. and Pesonen, L., 2003. Magnetic classification of stony meteorites: 1. Ordinary chondrites.
MAPS 38, N.5, pp. 251-268.
OFFICIAL CLASSIFICATION DATA SOURCE:
The Meteoritical Society
International Society for Meteoritics and Planetary Science
Lunar and Planetary Institute
Meteoritical Bulletin Database
Northwest Africa 13297
Basic information
Name:
Northwest Africa 13297
This is an OFFICIAL meteorite name.
Abbreviation:
NWA 13297
Observed fall:
No
Year found:
2020
Country:
Algeria
Mass:
1973 g
Classification
history:
Recommended:
LL3
This is 1 of 431 approved meteorites classified as LL3.
Comments:
Approved 2 May 2020
Writeup
Writeup from MB 109:
Northwest Africa 13297
(NWA 13297)
Algeria
Purchased: 2020
Classification: Ordinary chondrite (LL3)
History
: A sample comprised of many weathered pieces weighing 1973 g were found by meteorite prospectors in Algeria and sold to Mohamed Elguirah in Laayoune, Morocco. John Higgins and Carlos Muñecas Muñoz purchased the samples in 2020.
Physical characteristics
: Most samples are tabular in shape. One sample has an irregular ovoid shape with a dark brown weathered exterior. The cut face of the irregular sample shows a fresh, unweathered interior composed of abundant chondrules surrounded by fine-grained sulfide rims. FeNi grains occur within the interiors of chondrules. The unweathered interior is surrounded by a well-developed weathering rind with concentric cracks that surround unweathered interior. Material in the weathering rind is identical to tabular samples.
Petrography
: Description and classification (A. Love,
App
) Sample has a chondritic texture composed of distinct, close-packed chondrules with an average apparent diameter of 763 ?m (n=77) set within an opaque fine-grained, clastic matrix. Chondrules are surrounded by fine-grained rims of sulfide and have mesostasis commonly composed of isotropic glass and devitrified glass (dominant). Additional minerals are troilite, apatite and secondary calcite.
Geochemistry
: (A. Love,
App
) Olivine (Fa
16.7±10.2
(Fa
0.6-30.1
), Fe/Mn=36.6±11.8, n=12. Cr
2
O
3
in type II chondrules has an average of 0.22±0.10, n=10); low Ca-pyroxene (Fs
12.9±10.1
Wo
0.9±0.6
(Fs
1.7-34.5
Wo
0.2-2.5
), n=10).
Classification
: Ordinary chondrite (LL3, C-S3, W1-3) Based on chondrule size and magnetic susceptibility this sample is an LL chondrite. Estimated subtype for this sample is between 3.15 and 3.2 based on unequilibrated compositions, presence of isotropic glass mesostasis (<3.3), yellow CL in chondrule mesostasis (3.1-3.2) and presence of red luminescence in chondrule olivine <3.5) and low CL of matrix (>3.1).
Specimens
: John Higgins holds 1213 g including the 250 g main mass and Carlos Muñoz holds and additional 760 g of tabular fragments. Many spalled tabular fragments and an endcut weighing a total of 130 g are and a polished thin section are on deposit at
App
.
Data from:
MB109
Table 0
Line 0:
Place of purchase:
Laayoune, Morocco
Date:
P 2020
Mass (g):
1973
Pieces:
Many
Class:
LL3
Shock stage:
C-S3
Weathering grade:
W1-3
Fayalite (mol%):
16.7±10.2
Ferrosilite (mol%):
12.9±10.1
Wollastonite (mol%):
0.9±0.7
Magnetic suscept.:
4.33
Classifier:
A. Love, App
Type spec mass (g):
130.3
Type spec location:
App
Main mass:
John Higgins
Comments:
Submitted by Anthony Love
Institutions
and collections
Department of Geology,Appalachian State University
Catalogs:
References:
Published in Meteoritical Bulletin, no. 109, in preparation (2020)
Geography:
Coordinates:
Unknown.
Statistics:
This is 1 of 1232 approved meteorites from
Algeria
(plus 29 unapproved names) (plus 4 impact craters)
Also see:
This lists the most popular meteorites among people who looked up this meteorite.
Revision
history:
This lists important revisions made to data for this record.
GUARANTEED AUTHENTICITY
Member of the Meteoritical Society & International Meteorite Collectors Association #9822 The authenticity of this meteorite has a 100% guarantee. Signed Certificate of Authenticity Included. First class delivery and provenance provided exhibiting important details of the classification & petrography.
1cm scale cube is for reference purposes and not included with the meteorite.
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