| MetSoc Home Publications Contacts |
|
||
|
||
| Northwest Africa 8691 | |||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Basic information | Name: Northwest Africa 8691 This is an OFFICIAL meteorite name. Abbreviation: NWA 8691 Observed fall: No Year found: 2014 Country: (Northwest Africa) Mass:  66 g | ||||||||||||||||||||||||||||||||
| Classification history: |
This is 1 of 93 approved meteorites classified as LL4-6. [show all] Search for other: LL chondrites, LL chondrites (type 4-7), Ordinary chondrites, and Ordinary chondrites (type 4-7) | ||||||||||||||||||||||||||||||||
| Comments: | Approved 16 Apr 2015 | ||||||||||||||||||||||||||||||||
| Writeup |
Writeup from MB 104:
Northwest Africa 8691 (NWA 8691) (Northwest Africa) Purchased: 2014 Classification: Ordinary chondrite (LL4-6) History: One subrounded stone weighing 66 g was found in Morocco in 2014. David Holden acquired the sample from a meteorite prospector in Erfoud 2014. Physical characteristics: The stone is orangish-brown and has a rounded-angular shape. There is no relict fusion crust remaining on the exterior. The cut face of the interior of the stone is orangish-brown and shows chondrules, clasts and fresh flakes of metal. Petrography: Description and classification (A. Love, App): Sample displays brecciated structure containing chondrules, chondrule fragments and light and dark-colored clasts of various petrologic grades set within an oxidized, fine-grained fragmental matrix containing ~1.5 vol% FeNi metals. Clasts display weakly to totally recrystallized chondritic textures and shock-darkened and shock melted textures. Weakly recrystallized clasts display distinct chondrules in a recrystallized matrix. Totally recrystallized clasts lack distinct chondrules and have plagioclase grains with an average largest dimension of 43.45 μm. Chondritic host rock contains well-defined chondrules with average diameter of 0.7 mm. Three porphyritic pyroxene chondrules with zoned phenocrysts and low Fs compositions (Fs7.25-17.09) were observed within the matrix. Geochemistry: (A.Love, App) Olivine Fa34.2±0.7, N=16; Low Ca pyroxene Fs24.3±0.9Wo3.4±1.9, N=7; Fs10.7±4.5Wo1.0±0.2, N=3. Mean olivine composition is outside normal range for LL chondrites. Oxygen isotopes (K. Ziegler, UNM): analyses of acid-washed subsamples by laser fluorination gave, respectively, δ17O = 3.963, 4.079, 3.892; δ18O = 5.916, 5.731, 5.349; Δ17O = 0.839, 1.053, 1.068 (all per mil). Average of triplicate analyses of acid-washed subsamples by laser fluorination gave, respectively, δ17O = 3.978; δ18O = 5.665; Δ17O = 0.987 (all per mil). Oxygen isotopes plot in LL region above the TFL. Specimens: An endcut slice and small fragments weighing 12.99 g, a polished mount and polished thin section are currently on deposit at App. | ||||||||||||||||||||||||||||||||
| 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) App: Department of Geology, 572 Rivers St., Appalachian State University, Boone, NC 28608, United States (institutional address; updated 7 Mar 2013) |
||||||||||||||||||||||||||||||||
| 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 9933 approved meteorites from (Northwest Africa) (plus 1837 unapproved names) | ||||||||||||||||||||||||||||||||