Morocco
Found 2000
Achondrite (ungrouped)
A 368 g partially crusted stone was purchased in Rissani in 2001. Classification and mineralogy (T. Bunch and J. Wittke, NAU): cataclastic pyroxenite with randomly dispersed metal grains; partial recrystallization of matrix and along fractures of large (up to 5 mm) orthopyroxene grains. Mineral modes: orthopyroxene, 68 vol. %; metal, 12 vol. %; plagioclase, 8 vol. %; troilite, 3 vol. %; ilmenite, 3 vol. %; phosphate, 2 vol. %; spinels, 2 vol. %; and augite 2 vol. %. Orthopyroxene, Fs28Wo3; kamacite, Ni = 4.8 to 5.4 wt. %; taenite, Ni = 31.4 to 36.7 wt. %; plagioclase, An90; spinel #1, Al2O3 = 61 wt. %, MgO = 21.4 wt. %, FeO = 13.2 wt. %; spinel #2, Cr2O3 = 35.9 wt. %, Al2O3 = 33.0 wt. %, MgO = 17.9 wt. %, FeO = 13.1 wt. %; augite, Fs13Wo43. Oxygen isotope composition is somewhat outside the range of HED and closest to brachinites and IAB-IIICD irons (R. N. Clayton, UChi): δ18O = +3.78 per mil., δ17O = +1.47 per mil, Δ17O = +3.78 per mil. Cosmic ray exposure age (O. Eugster, UBE) of 18.6 ± 2.0 Ma falls on the major CRE cluster of the HED meteorites. Not paired with NWA 1827 or 1879 mesosiderite C. Shock level, S1. Weathering grade, W1. Specimens: type specimens: 13.8 g, NAU, 11.5 g with O. Eugster, UBE; main mass, Fectay.
Morocco or Algeria
Purchased April 2003
Achondrite (ungrouped)
A 137 g light tan to rusty brown, fully crusted stone was purchased in Rissani, Morocco in April 2003. Description and classification (T. Bunch and J. Wittke, NAU; A. Irving and S. Kuehner, UWS): composed mainly of approximately mm-sized, randomly oriented pigeonite (Fs64-64.8Wo5.6-6.4) with very fine, parallel exsolution lamellae of augite (Fs38-49.1Wo36.7-23), and interstitial, recrystallized plagioclase (<0.10 mm in size, ~An86Or0.5) with prominent triple junctions, and rare, unrecrystallized, tabular plagioclase relicts (<1 mm, zoned from An80to An89). FeO/MnO ratios for all pyroxenes range from 59.5 to 68.7 g/g (average = 64.7 g/g). Only small amounts of pyroxene are present in the recrystallized zones. Accessory minerals occurring predominantly in the recrystallized plagioclase zones include a silica polymorph, chromite [Cr/(Cr + Al) = 0.83, Fe/(Fe + Mg) = 0.67], ilmenite (53.5 wt. % TiO2, 43.6 wt. % FeO; with small baddeleyite inclusions), merrillite (some with minor amounts of Na2O, MgO, and FeO), Zn-bearing troilite, pentlandite, Cr-ulvöspinel and altered Fe metal (associated with minor troilite, barite and calcite). Shock damage is not apparent and, with the exception of the oxidation of minor metal, weathering effects are very low. Oxygen isotopes (D. Rumble, CIW): replicate analyses by laser fluorination gave δ17O = - 0.15 ± 0.1, δ18O = 3.27 ± 0.2, Δ17O = -1.57 ± 0.03 per mil. In its texture, mineral mode, mineral compositions and oxygen isotope composition NWA 2400 is nearly identical to the non-Vesta anomalous achondrite NWA 011 (Yamaguchi et al., 2002; Promprated et al., 2003), which strongly indicates that these two stones are paired. Specimens: type specimen 20.2 g and three polished thin sections, NAU; main mass, anonymous purchaser.
References
Yamagouchi A., Clayton R. N., Mayeda T., Ebihara M., Oura Y., Miura Y. N., Hjaramura H., Misawa K., Kolima H. & Nagao K., 2002, A new source of basaltic meteorites inferred from Northwest Africa 011, Science 296, 334-336.
Promprated P., Taylor L. A., Anand M., Rumble III D., Korochantseva E. V., Ivanova M. A., Lorentz C. A. & Nazarov M. A., 2003, petrology and oxygen isotopic compositions of anomalous NWA 011. In Lunar and Planetary Science XXXIV. Lunar and Planetary Institute, Houston, TX (CD-ROM), Abstract 1757.
Northwest Africa
Purchased October 2004
Achondrite (ungrouped)
A 4.2 kg, partially crusted stone was purchased in Erfoud, Morocco. Description and classification (T. Bunch and J. Wittke, NAU), results from one thin section (2.4 cm2): mostly recrystallized into fine-grained (<0.5 mm, avg. = 0.185 mm) polygonal and subhedral grains with the exception of several medium to large (1.2-3.0 mm) orthopyroxene grains that contain very small olivine (<0.1 mm) inclusions. Very homogeneous assemblage, olivine and orthopyroxene analyses are within the precision of the electron microprobe (± 0.15 mol %). Olivine, Fa18.9 (FeO/MnO = 38.1 g/g); orthopyroxene, Fs16.8Wo2.9 (FeO/MnO = 20.0 g/g); plagioclase, An15.1Or4.7; metal (only taenite found), Ni = 18.9 wt. %; chromite (only one grain found), Cr/(Cr+Al) = 84.5; FeS, Ni = 1.42 wt. % and Co = 0.28 wt. %, minor merrillite. Oxygen isotope replicate analyses (D. Rumble, CIW) of acid washed, bulk sample by lased fluorination gave δ17O = 3.23 and 2.98, δ18O = 5.03 and 4.37 and Δ17O = 0.614 and 0.708. Formerly classified as an H7. Weathering grade, W2/3 with staining; shock level, S1. Specimens: type sample, 23.2 g, NAU; main mass, Strope/Farmer.
Northwest Africa
Found 2005
Achondrite (ungrouped)
History: A large number of pieces were collected within a small strewn field of ~15 m diameter in Algeria and sold in Erfoud, Morocco. Physical characteristics: Most of the 586 g mass of fragments are without fusion crust, are dark brown in color and show extensive surface weathering. Petrography (T. Bunch and J. Wittke, NAU): partially recrystallized polymict breccia that contains at least two distinct lithologies: (A) medium-grained clasts (< 2mm) of untwinned orthopyroxene without discernable exsolution lamellae and a roughly equal amount of complex, polysynthetically twinned plagioclase partially converted to maskelynite and (B) medium-grained, partially recrystallized pigeonite with minor development of exsolution lamellae and twinning with inclusions of simple, albite-twinned plagioclase together with a fine-grained assemblages (< 0.1 mm) of tridymite, metal, and plagioclase at recrystallization boundaries. Both lithologies are set in a fine-grained, partially recrystallized matrix of pyroxenes and plagioclase compositionally similar to lithologies A and B. Minor minerals include Al-rich chromite, sulfide, tridymite, phosphate and metal. Geochemistry: lithology (A) orthopyroxene cores are Fs22.0-25.3Wo2.5 and the FeO/MnO = 24-27and have replacement grain margins of Fs33.8Wo7.2 that in turn have exsolved Ca-rich pyroxene, Plagioclase composition is An99.5Or0.5. Lithology (B) pigeonite is Fs38.1Wo11.1 and the plagioclase is An94.8Or5.6.. Classification: Achondrite (ungrouped). Overall characteristics of this meteorite are similar to clast material in some mesosiderites and may represent a large, separated mesosiderite clast. Shock level is S3 (maskelynite threshold) and the stone is moderately weathered. Type specimens: A total of 23g are on deposit at NAU. Mr. Blaine Reed holds the main mass.
Reference
Irving, A. J., Bunch, GT. E., Rumble, III, D. & Larson, T. E., 2005, Metachondrites: Recrystallized and/or residual mantle rocks from multiple, large chondritic parent bodies: 68th Meteoritical Society Meeting, #????.
Algeria
Find: 2006
Achondrite (ungrouped, lodran-like)
History: A fully crusted, complete stone of 625 g was recovered from the lower Algerian desert in June 2006 and purchased in Erfoud in August 2006 by A. Aaronson. Petrography (T. Bunch and J. Wittke, NAU; T. Irving, UWA): Protogranular texture with a grain size range of 0.3 to 3.4 mm (mean = 1.35 mm) for silicates and 0.3 to 5 mm for metal (mean = 2.4 mm). Modal analyses (6.4 cm2; vol. %): orthopyroxene, 37; olivine, 32; metal, 30; sulfide, 1. Several metal grains have taenite cores mantled by kamacite. Taenite grain shape is roughly similar to the outline of the entire metal grain; embryonic plessite is evident in a few taenite cores. No directional fabric was recognized. Fusion crust is lightly to moderately altered and weathering is limited to minor oxidation of kamacite with the presence of minor oxide veining. Geochemistry: Olivine, Fa12.3±0.2, FeO/MnO = 32 g/g; orthopyroxene, Fs11.2±0.02Wo1.2, FeO/MnO = 19 g/g; taenite, Ni = 7.9 wt. %; kamacite, Ni = 4.6 wt. %. Oxygen isotopes (D. Rumble, CIW): A cleaned and metal-free sample was analyzed by laser fluorination. Replicate analyses are respectively, δ17O = 1.129 and 1.220; δ18O = 2.527 and 2.661; Δ17O = -0.2006 and -0.1802. Classification: Achondrite, ungrouped lodran-like. Petrography and geochemistry are consistent with lodranites, oxygen isotopes are inconsistent with lodranites/acapulcoites and are closest to the 1AB irons and winonaite trend. Specimens: 20.3 g and one polished thin section are on deposit at NAU. The main mass holder is anonymous.
Algeria
Find: 2005
Achondrite (anomalous)
History: This partial stone was found in 2005 and purchased in Erfoud, Morocco in October 2005. Physical description: The exterior is dark brown where not covered by moderately weathered fusion crust. The total weight is 137g. Petrography (T. Bunch and J. Wittke, NAU): Igneous textures include hypidimorphic-granular, ophitic, and poililitic (orthopyroxene oikocrysts enclose olivine). NWA 4284 is composed of mm to sub mm-sized grains of (in order of abundance) orthopyroxene, olivine, plagioclase, diopside, FeS, and chromite. Taenite metal is relegated to rare, isolated clusters of coarser-grained orthopyroxene-olivine-plagioclase-taenite. Geochemistry: Orthopyroxene, Fs24.5Wo3.5, FeO/MnO = 28-30 g/g; olivine, Fa24.6, FeO/MnO = 46-54 g/g; plagioclase. An11Or5.3; diopside, Fs8.2Wo44.2; chromite, Cr/(Cr+Al) = 0.88; and taenite, Ni = 21.5 wt % (no kamacite was found). Oxygen isotopes (D. Rumble, CIW): a cleaned and metal-free sample was analyzed by laser fluorination. Replicate analyses are, respectively, δ17O = 3.253, 3.227; δ18O = 4.195. 4.247; Δ17O = 1.046, 0.993 (all ‰). Classification: Achondrite, (anomalous). Mineral compositions and oxygen isotopes indicate that this stone has an L chondrite heritage, but the lack of chondrules and obvious igneous textures, indicate a late melting event. Lightly weathered and lightly shocked (S2). Type specimens: A total of 21 g and one thin section are on repository at NAU. Mr. Edwin Thompson is the main mass holder.
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| ID | Location | Date | Class. | Mass (g) | State | Olivone | Pyroxene | Comments |
|---|---|---|---|---|---|---|---|---|
| NWA 2653 | Zagora, Morocco | 2004 | ACHOND | 189 | S1, W4 | Fa28.5 (FeO/MnO = 65.2 g/g) | Fs23.3Wo8.0 (FeO/MnO = 48.2 g/g) | paired with NWA 3133 |