NWA 13446 ( 1,700 g )

Frontside polished,
Vorderseite poliert.
 
Northwest Africa 13446 (NWA 13446)
Algeria
Purchased: 2020 Jun
Classification: Ungrouped achondrite
History: Purportedly found in Algeria and purchased by Habib Naji in June 2020 from a dealer in Adrar, Algeria.
Petrography: (A. Irving, UWS and P. Carpenter, WUSL) The specimen has an igneous cumulate texture and consists predominantly of zoned olivine (~90 vol.%) with intercumulus assemblages composed of low-Ca pyroxene (mostly pigeonite), subcalcic augite and sodic plagioclase-like glass with accessory chromite, troilite and very rare spherical grains of metal (kamacite and taenite).
Geochemistry: Olivine (Fa19.8±3.7, range Fa15.8-27.9, FeO/MnO = 47-54, N = 11), low-Ca pyroxene (Fs28.8Wo4.6, FeO/MnO = 26), pigeonite (Fs26.6±4.4Wo10.4±4.7, range Fs18.3-30.6Wo6.5-18.9, FeO/MnO = 26-30, N = 6), subcalcic augite (Fs34.2±6.7Wo27.2±5.0, range Fs27.3-43.3Wo23.0-34.2, FeO/MnO = 27-35, N = 4), plagioclase-like glass (Ab65.4-86.0An15.7-5.8Or18.9-8.2, N = 4), kamacite (Ni = 1.6 wt.%), taenite (Ni = 36.4 wt.%). Oxygen isotopes (K. Ziegler, UNM): analyses of acid-washed subsamples by laser fluorination gave, respectively, δ17O 3.638. 3.614, 3.623; δ18O 4.887, 4.859, 4.947; Δ17O 1.058, 1.049, 1.012 per mil (all data linearized).
Classification: Achondrite (igneous, ultramafic, ungrouped). This specimen is an almost metal-free, olivine-dominated igneous achondrite with oxygen isotope affinities to L chondrites. Olivine exhibits compositional zoning from core values typical of H chondrites to rim values more typical of L chondrites, and intercumulus pyroxene also exhibits zoning from pigeonite cores to subcalcic augite rims.
Specimens: 54 g including one polished thin section at UWB; remainder with Mr. H. Naji.
 
Place of purchase:
Adrar
Date:
P 2020 Jun
Mass (g):
6484
Pieces:
several
Class:
Achondrite-ung
Shock stage:
low
Weathering grade:
low
Fayalite (mol%):
19.8±3.7
Ferrosilite (mol%):
28.8; 26.6±4.4; 34.2±6.7
Wollastonite (mol%):
4.6; 10.4±4.7; 27.2±5.0
Classifier:
A. Irving, UWS, and P. Carpenter, WUSL
Type spec mass (g):
54.0
Type spec location:
UWB
Main mass:
H. Naji
Comments:
Work name HN 630; submitted by A. Irving