|
Northwest Africa 13312 | |||||||||||||||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Basic information | Name: Northwest Africa 13312 This is an OFFICIAL meteorite name. Abbreviation: NWA 13312 Observed fall: No Year found: 2019 Country: (Northwest Africa) Mass: 45 g | ||||||||||||||||||||||||||||||
Classification history: |
This is 1 of 142 approved meteorites classified as Achondrite-ung. [show all] Search for other: Achondrites, Ungrouped achondrites | ||||||||||||||||||||||||||||||
Comments: | Approved 13 Jun 2020 | ||||||||||||||||||||||||||||||
Writeup |
Writeup from MB 109:
Northwest Africa 13312 (NWA 13312) (Northwest Africa) Purchased: 2019 Sep Classification: Ungrouped achondrite History: Purchased by Mbark Arjdal in September 2019 from a dealer in Timbuktu, Mali. Petrography: (A. Irving, UWS and P. Carpenter, WUSL) Fresh specimen with a complex igneous poikilitic texture and variable grainsize composed predominantly of coarser grained zoned pyroxene oikocrysts (0.5-2 mm) enclosing subordinate olivine chadacrysts (0.1-0.3 mm), plus finer grained interstitial regions. Accessory phases are chromite, troilite, and very rare small grains of taenite and slightly stained kamacite; no phosphates were observed. Pyroxenes are zoned from orthopyroxene cores (exhibiting prominent polysynthetic twinning) to more ferroan pigeonite and subcalcic augite rims. Sporadic very large homogeneous macrocrysts (up to 0.6 cm across) of both olivine and orthopyroxene are also present. Interstitial regions consist of subparallel intergrowths of acicular calcic plagioclase, high-Ca pyroxene and silica polymorph accompanied by minor ilmenite, Ni-bearing pyrrhotite and pentlandite. Geochemistry: Olivine (Fa20.4-35.1, FeO/MnO = 47-51, N = 10), orthopyroxene cores (Fs11.8-14.2Wo0.2-0.3, FeO/MnO = 31-34, N = 4), low-Ca pyroxene rims (Fs23.7-35.2Wo2.0-4.9, FeO/MnO = 28-32, N = 6), subcalcic augite (Fs32.0-40.8Wo33.7-24.0, FeO/MnO = 25-27, N = 5), pigeonite (Fs29.4Wo14.7; Fs45.1-47.0Wo7.1-9.7; FeO/MnO = 26-30; N = 3), plagioclase (An68.2-86.4Or2.3-0.7, N = 3). Magnetic susceptibility log χ (× 10-9 m3/kg) = 3.07. Classification: Achondrite (ungrouped, igneous, poikilitic, metal-poor). Specimens: 9.7 g including one polished thin section at UWB; remainder with Mr. M. Arjdal. | ||||||||||||||||||||||||||||||
Data from: MB109 Table 0 Line 0: |
|
||||||||||||||||||||||||||||||
Institutions and collections |
UWS: University of Washington, Department of Earth and Space Sciences, 70 Johnson Hall, Seattle, WA 98195, United States (institutional address; updated 15 Jan 2012) WUSL: Washington Univ., One Brookings Drive, St. Louis, MO 63130, United States (institutional address; updated 17 Oct 2011) UWB: University of Washington, Burke Museum of Natural History and Culture, Box 353010 Seattle, WA 98195, United States (institutional address; updated 9 Oct 2023) |
||||||||||||||||||||||||||||||
Catalogs: |
| ||||||||||||||||||||||||||||||
References: | Published in Meteoritical Bulletin, no. 109, in preparation (2020)
| ||||||||||||||||||||||||||||||
Geography: |
Statistics: This is 1 of 9589 approved meteorites from (Northwest Africa) (plus 1869 unapproved names) | ||||||||||||||||||||||||||||||
Also see: |
This lists the most popular meteorites among people who looked up this meteorite.
| ||||||||||||||||||||||||||||||
Revision history: |
This lists important revisions made to data for this record.
|