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Northwest Africa 15500 | |||||||||||||||||||||||||||||||
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Basic information | Name: Northwest Africa 15500 This is an OFFICIAL meteorite name. Abbreviation: NWA 15500 Observed fall: No Year found: 2022 Country: (Northwest Africa) Mass: ![]() | ||||||||||||||||||||||||||||||
Classification history: |
This is 1 of 102 approved meteorites classified as Lunar. [show all] Search for other: Lunar meteorites | ||||||||||||||||||||||||||||||
Comments: | Approved 20 Dec 2022 | ||||||||||||||||||||||||||||||
Writeup![]() |
Writeup from MB 111:
Northwest Africa 15500 (NWA 15500) (Northwest Africa) Purchased: Mar 2022 Classification: Lunar meteorite History: Purchased online in March 2022 by Craig Zlimen froma meteorite dealer in Algeria. Physical characteristics: Single stone with no visible fusion crust. A slice of the interior reveals the stone to be divided in half into two different rock types. Petrography: (D. Sheikh, Cascadia) Specimen represents a dimict breccia comprised of two distinct (but genetically related) lithologies separated by a sharp contact: Lith A) A feldspathic fragmental breccia composed of mm-sized angular to subangular lithic and mineral clasts set within a fine-grained matrix. Clast lithologies identified in this sample include anorthosites, norites, olivine norites, troctolites, pink spinel troctolites, pink spinel anorthosites, and impact melt clasts; clasts lithologies are predominantly Mg-suite in composition, with minor input from lunar ferrous anorthosite. Accessory phases include ilmenite, SiO2-rich glass, and merrillite. Lith B) A clast-poor troctolitic impact melt composed of compositionally zoned olivine and minor high-Ca pyroxene dendrites (Av. grain size ~10 µm, and unzoned plagioclase laths (mix of both cracked and smooth, Av. grain size ~0.5 mm). Clast lithologies identified include anorthosites, pink spinel anorthosites, and troctolites. Accessory phases include SiO2-rich glass and ülvospinel. Geochemistry: Lith A [Olivine (Fa17.8±12.1, range Fa4.4-53.3, Fe/Mn=85±14, n=76), Low-Ca Pyroxene (Fs23.9±13.8Wo3.4±1.2, range Fs10.5-52.2Wo0.8-4.6, Fe/Mn=55±8, n=23), Pigeonite (Fs33.0±10.1Wo10.7±3.3, range Fs19.1-56.6Wo6.3-17.0, Fe/Mn=55±7, n=16), High-Ca Pyroxene (Fs15.8±6.6Wo38.1±5.3, range Fs5.8-29.6Wo26.0-45.7, Fe/Mn=50±10, n=15), Calcic Plagioclase (An96.5±0.6, range An94.9-98.0, n=79), Pink Spinel (Cr#=3.9±0.2, Mg#=85.5±1.3, n=70)]; Lith B [Olivine (Fa21.6±5.8, range Fa9.1-30.7, Fe/Mn=79±11, n=35), Low-Ca Pyroxene (Fs15.7±0.8Wo4.3±0.1, range Fs15.2-16.3Wo4.3-4.4, Fe/Mn=57±4, n=2), High-Ca Pyroxene (Fs27.4±12.9Wo39.5±2.7, range Fs8.6-37.4Wo36.8-43.2, Fe/Mn=46±5, n=4), Calcic Plagioclase (An95.8±0.8, range An94.4-97.9, n=40), Pink Spinel (Cr#=3.9±0.1, Mg#=82.0±1.3, n=19)]. Classification: Lunar (dimict breccia). The unusual presence of bonifide pink spinel anorthosite clasts that contain pink spinel compositionally similar to those measured by the Moon Mineralogy Mapper imaging spectrometer (M^3) suggest derivation of this specimen from a previously unsampled region on the lunar surface. Specimens: 20.2 g at Cascadia, main mass with Craig Zlimen. | ||||||||||||||||||||||||||||||
Data from: MB111 Table 0 Line 0: |
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Institutions and collections |
Cascadia: Cascadia Meteorite Laboratory, Portland State University, Department of Geology, Room 17 Cramer Hall, 1721 SW Broadway, Portland, OR 97201, United States; Website (institutional address; updated 28 Oct 2011) |
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Catalogs: |
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References: | Published in Meteoritical Bulletin, no. 111, in preparation (2022)
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Photos: |
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Geography: |
Statistics: This is 1 of 9092 approved meteorites from (Northwest Africa) (plus 1875 unapproved names) |