![]() |
||
|
Northwest Africa 8739 | |||||||||||||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Basic information | Name: Northwest Africa 8739 This is an OFFICIAL meteorite name. Abbreviation: NWA 8739 Observed fall: No Year found: 2013 Country: (Northwest Africa) Mass: ![]() | ||||||||||||||||||||||||||||
Classification history: |
This is 1 of 400 approved meteorites classified as Eucrite-pmict. [show all] Search for other: Achondrites, Eucrites, and HED achondrites | ||||||||||||||||||||||||||||
Comments: | Approved 16 Feb 2015 | ||||||||||||||||||||||||||||
Writeup![]() |
Writeup from MB 104:
Northwest Africa 8739 (NWA 8739) (Northwest Africa) Purchased: 2013 Classification: HED achondrite (Eucrite, polymict) History: Purchased by Blaine Reed from Eegooblago Meteorites at the Denver Gem and Mineral Show 2013. Physical characteristics: Single stone, smooth brown weathered exterior. A saw cut reveals a breccia with scattered clasts up to ~1 cm set a in fine-grained, gray, groundmass. Petrography: (C. Agee, UNM) Microprobe examination of a polished mount shows ~55% pyroxene and ~40% plagioclase. Accessory silica, troilite, chromite, ilmenite, and Fe-metal. Several different microtextures are present; there are numerous fragmental pyroxene and plagioclase grains up to ~300 μm, clasts with quench mesostasis and skeletal pyroxenes, clasts with acicular plagioclase or pyroxene intergrowths. Most pyroxenes show strong igneous zoning with En-rich cores and Fs/Wo-rich rims, however there is also a minor population of pyroxenes that appear to be more equilibrated with fine exsolution lamellae. Geochemistry: (C. Agee and N. Muttik, UNM) EMPA. Pyroxene Fs45.6±10.9Wo10.1±3.0, Fe/Mn=31±2, n=25; plagioclase Or0.6±0.4Ab10.3±3.6An 89.1±4.0, n=4. Oxygen isotopes (K. Ziegler, UNM): acid-washed material analyzed in 2 replicates by laser fluorination gave, respectively δ18O=3.420, 2.990; δ17O=1.508, 1.312; Δ17O= -0.298, -0.267 (all per mil). Classification: Achondrite (polymicy eucrite) Unequilibrated basalt with a range of pyroxene compositions consistent with Type-2 eucrites (Takeda and Graham, 1991); a polymict breccia similar in texture and composition to Pasamonte. Specimens: 20.0 g including a probe mount on deposit at UNM, Reed holds the main mass. | ||||||||||||||||||||||||||||
Bibliography: |
| ||||||||||||||||||||||||||||
Data from: MB104 Table 0 Line 0: |
|
||||||||||||||||||||||||||||
Plots: | O isotopes: | ||||||||||||||||||||||||||||
Institutions and collections |
UNM: Institute of Meteoritics
MSC03 2050
University of New Mexico
Albuquerque NM 87131-1126
USA, United States; Website (institutional address; updated 12 Feb 2015) Reed: Blaine Reed, P.O. Box 1141, Delta, CO 81416, United States; Website (private address) |
||||||||||||||||||||||||||||
Catalogs: |
| ||||||||||||||||||||||||||||
References: | Published in Meteoritical Bulletin, no. 104, MAPS 52, 2284, Octover 2017, http://onlinelibrary.wiley.com/doi/10.1111/maps.12930/full
| ||||||||||||||||||||||||||||
Geography: |
Statistics: This is 1 of 9429 approved meteorites from (Northwest Africa) (plus 1876 unapproved names) |