| MetSoc Home Publications Contacts |
|
||
|
||
| Northwest Africa 15994 | |||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Basic information | Name: Northwest Africa 15994 This is an OFFICIAL meteorite name. Abbreviation: NWA 15994 Observed fall: No Year found: 2023 Country: (Northwest Africa) Mass:  17 g | ||||||||||||||||||||||||||||||
| Classification history: |
This is 1 of 4 approved meteorites classified as Achondrite-prim-ung. [show all] Search for other: Primitive achondrites, Ungrouped achondrites | ||||||||||||||||||||||||||||||
| Comments: | Approved 15 Jul 2023 | ||||||||||||||||||||||||||||||
| Writeup |
Writeup from MB 112:
Northwest Africa 15994 (NWA 15994) (Northwest Africa) Purchased: 2023 Classification: Ungrouped primitive achondrite History: Shun-Chung Yang purchased many small samples totaling 17g from a Moroccan dealer in 2023. Physical characteristics: Samples show some weak orientation features but lack fusion crust. The cut face shows samples are crystalline mixtures of olivine and metal. Petrography: Description and classification (A. Love, App) Sample shows a protogranular texture composed of (vol%): 888 µm (n=22) olivine (68), anhedral, interstitial, birefringent plagioclase (7), and irregularly shaped masses of FeNi (23). Plagioclase surrounds metal masses. Olivine has subgrains that meet at 120º grain boundaries. Taenite, occurs within kamacite, as 20-40 µm droplets or octagonal masses. Additional minerals are: trace high Ca pyroxene (occurring as melt inclusions within olivine), troilite, Ti-bearing chromite, merrillite and apatite. Geochemistry: (A. Love, App) Olivine (Fa44.5±0.3, CaO=0.42±0.3, Fe/Mn=67.6±1.6, n=12); high Ca pyroxene (Fs11.8-14.4Wo49.4-49.9, Fe/Mn=71.7-67.4 n=2); plagioclase (An46.6±2.7Or1.6±0.6, n=5; An24.3±2.5Or5.3±0.8 n=6); Kamacite (Fe=91.8±0.2wt%, Ni=6.8±0.2wt%, Co=1.3±0.1 wt%, n=5); taenite (Fe=78.9±1.4wt%, Ni=20.0±1.5 wt%, Co=0.9±0.0wt%, n=3). Oxygen Isotope Composition (D. Ibarra, BrownU) Acid washed bulk powder analyzed by laser fluorination gave δ17O =2.592; δ18O =6.564; Δ17O = -0.861, (all values relative to VSMOW-SLAP2, slope 0.528). Samples were normalized to San Carlos olivine values of Sharp and Wostbrock (2021). Sample plots below the TFL and in a region near ureilites. Classification: Primitive achondrite (ungrouped) Based on texture, mineral compositions and metal abundance, sample is a primitive achondrite. Ferroan olivine compositions as well as oxygen isotope compositions and metal abundance make this sample distinct from brachinites, ureilites and the acapulcoite/lodranite clan. This sample may be related to the ungrouped achondrites NWA 6962 and 7680. Specimens: Shun-Chung Yang (S-R meteorites) holds the main masses. Several small fragments weighing a total of 3.4 g and a polished thin section are on deposit at App. | ||||||||||||||||||||||||||||||
| Bibliography: |
| ||||||||||||||||||||||||||||||
| Data from: MB112 Table 0 Line 0: |
|
||||||||||||||||||||||||||||||
| Plots: | O isotopes: | ||||||||||||||||||||||||||||||
| Institutions and collections |
App: Department of Geology, 572 Rivers St., Appalachian State University, Boone, NC 28608, United States (institutional address; updated 7 Mar 2013) BrownU: Joseph Boesenberg Brown University Dept of Earth, Environmental and Planetary Sciences (DEEPS) 324 Brook Street Providence, RI 02912 , United States (institutional address; updated 26 Oct 2023) |
||||||||||||||||||||||||||||||
| Catalogs: |
| ||||||||||||||||||||||||||||||
| References: | Published in Meteoritical Bulletin, no. 112, in preparation (2023)
| ||||||||||||||||||||||||||||||
| Photos: |
| ||||||||||||||||||||||||||||||
| Geography: |
Statistics: This is 1 of 9429 approved meteorites from (Northwest Africa) (plus 1876 unapproved names) | ||||||||||||||||||||||||||||||