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Northwest Africa 2999 | |||||||||||||||||||||||
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Basic information | Name: Northwest Africa 2999 This is an OFFICIAL meteorite name. Abbreviation: NWA 2999 Observed fall: No Year found: 2004 Country: (Northwest Africa) Mass: ![]() | ||||||||||||||||||||||
Classification history: |
This is 1 of 46 approved meteorites classified as Angrite. [show all] Search for other: Achondrites, Angrites | ||||||||||||||||||||||
Comments: |
Approved 16 Jan 2006 Revised 3 Feb 2006: Revised writeup | ||||||||||||||||||||||
Writeup![]() |
Writeup from MB 90:
Northwest Africa 2999 Morocco or Algeria Find: 2004 Achondrite (angrite) History: Twelve individual dark brown stones totaling 392 g, each with a thin fusion crust, were purchased from a Moroccan dealer in Tagounite by G. Hupé in August 2004. Physical Characteristics: Grain size is predominantly from 0.1 to 0.5 mm, but all stones have irregularly distributed, larger yellowish plagioclase grains (up to 6 mm across) exhibiting an iridescent luster. Petrography: (A. Irving and S. Kuehner, UWS; T. Bunch and J. Wittke, NAU) Based upon examination of thin sections of all separate stones, this meteorite is texturally heterogeneous. Terrestrial weathering has resulted in partial replacement of metal and minor grain boundary staining by iron hydroxides. The overall texture is protogranular, but there are large porphyroclasts of anorthite, spinel, and polygranular olivine. Anorthite also occurs as narrow (10–20 µm wide) coronas around spinel grains adjacent to clinopyroxene and both spinel and diopside are compositionally zoned away from the coronas. Texturally, this meteorite is very different from most angrites. Geochemistry: The major minerals are Ca-rich olivine (Fa39.8–41.0; FeO/MnO = 77–97; CaO = 0.6–1.3 wt%), Al,Ti-bearing diopside (Fs9.6–11.3Wo53–54; FeO/MnO = 55–130; Al2O3 = 5–9, TiO2 = 0.5–2.4 [both wt%]), minor Cr-pleonaste spinel (Mg/(Mg+Fe) = 0.44–0.47, Al2O3 = 55–60, Cr2O3 = 4.7–8.7 [both wt%]), pure anorthite (containing Na2O < 0.02 wt%), and kamacite, troilite, and S-bearing calcium silicophosphate. Oxygen isotopes: (D. Rumble, CIW) Triplicate analyses of acid-washed whole rock samples by laser fluorination gave, respectively, δ18O = 3.839, 4.093, 4.154; δ17O = 1.974, 2.054, 2.095; ∆17O = −0.041, −0.095, −0.086 (all ‰). Classification: Achondrite (angrite). Specimens: A 22 g type specimen and one polished thin section are on deposit at NAU. Three polished thin sections are on deposit at UWS. GHupé holds the main mass. | ||||||||||||||||||||||
Data from: MB90 Table 2 Line 191: |
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Plots: | O isotopes: | ||||||||||||||||||||||
Institutions and collections |
NAU: Geology, Bldg 12
Knoles Dr
Northern Arizona University, Flagstaff, AZ 86011, United States; Website (institutional address; updated 12 Apr 2012) UWS: University of Washington, Department of Earth and Space Sciences, 70 Johnson Hall, Seattle, WA 98195, United States (institutional address; updated 15 Jan 2012) CIW: Carnegie Insitution Washington, Geophysical Laboratory, 5251 Broad Branch Rd., NW, Washington DC 20015, United States (institutional address) GHupé: Gregory M. Hupé, 9003 Placid Lakes Blvd., Lake Placid, FL 33852, United States; Website (private address) |
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Catalogs: |
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References: | Published in Meteoritical Bulletin, no. 90, MAPS 41, 1383-1418 (2006)
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Photos: |
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Geography: |
Statistics: This is 1 of 9429 approved meteorites from (Northwest Africa) (plus 1876 unapproved names) |