![]() |
||
|
Northwest Africa 6704 | |||||||||||||||||||||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Basic information | Name: Northwest Africa 6704 This is an OFFICIAL meteorite name. Abbreviation: NWA 6704 Observed fall: No Year found: unknown Country: Algeria Mass: ![]() | ||||||||||||||||||||||||||||||||||||
Classification history: |
This is 1 of 138 approved meteorites classified as Achondrite-ung. [show all] Search for other: Achondrites, Ungrouped achondrites | ||||||||||||||||||||||||||||||||||||
Comments: |
Approved 17 May 2011 Revised 11 Mar 2012: Updated mass | ||||||||||||||||||||||||||||||||||||
Writeup![]() |
Writeup from MB 99:
Northwest Africa 6704 (NWA 6704) Algeria Purchased: Jan-May 2011 Classification: Ungrouped achondrite History: A single, dense, yellowish-green stone was found in pieces in Algeria, and was purchased in February 2011 at the Tucson Gem and Mineral Show and over subsequent weeks from Moroccan dealers by Greg Hupé. Physical characteristics: The reassembled 42 pieces (plus some granular debris) fit together as a single ovoid mass (8387 g) with rounded, shiny exterior surfaces and small patches of remnant black fusion crust. The very fresh interior is mostly pale yellowish green with sporadic darker brownish grains and sparsely distributed tiny grains of opaque oxide and silvery metal. Petrography: (A. Irving and S. Kuehner, UWS): Overall medium grained with an igneous cumulate texture. Small grains of olivine (0.5-0.8 mm) and chromite (0.1-0.6 mm) enclosed within large (to 4 mm) orthopyroxene oikocrysts, which are in turn surrounded by large optically continuous, intercumulus grains of untwinned albite and <0.1 mm awaruite. The silicates contain curvilinear trains of tiny rounded inclusions (2-20 μm), which appear on polished surfaces to be empty bubbles with smooth rounded walls. Geochemistry: Olivine (Fa51.6-53.2; FeO/MnO=120-140; NiO=0.9-1.0 wt.%), orthopyroxene (Fs41.6-42.4Wo2.8-3.6, FeO/MnO=81-82; Cr2O3=0.3 wt.%), plagioclase (Ab92-93An4-3Or4). Oxygen isotopes (R. Tanaka, OkaU): replicate analyses of acid-washed material by laser fluorination gave: δ17O 1.015, 0.880; δ18O 3.922, 3.613; Δ17O -1.048, -1.020 per mil. Classification: Achondrite (ungrouped). This specimen is unlike other achondrites in its combined features: relatively ferroan mafic silicate minerals with elevated FeO/MnO ratios and anomalous Ni contents, extremely sodic plagioclase, very Ni-rich metal, and oxygen isotopic composition that plots within the field for acapulcoites-lodranites. Weathering is low and limited to minor coatings of pale orange desert dust on broken surfaces. Unshocked. Specimens: A total of 20.5 g of type material and two polished thin sections are on deposit at UWS. The remaining material is held by GHupé. | ||||||||||||||||||||||||||||||||||||
Data from: MB99 Table 0 Line 0: |
|
||||||||||||||||||||||||||||||||||||
Plots: | O isotopes: | ||||||||||||||||||||||||||||||||||||
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) GHupé: Gregory M. Hupé, 9003 Placid Lakes Blvd., Lake Placid, FL 33852, United States; Website (private address) Hupe: (old address—now see GHupé or AHupé) G. and A. Hupe, 2616 Lake Youngs Court SE, Renton, WA 98058., United States (private address) OkaU: Institute for Study of the Earth's Interior, Okayama University, Misasa Tottori 682-0193, Japan (institutional address) |
||||||||||||||||||||||||||||||||||||
Catalogs: |
| ||||||||||||||||||||||||||||||||||||
References: | Published in Meteoritical Bulletin, No. 99, April 2012, MAPS 47, E1-E52 (2012) [published online only]
| ||||||||||||||||||||||||||||||||||||
Photos: |
| ||||||||||||||||||||||||||||||||||||
Geography:![]() |
Statistics: This is 1 of 1303 approved meteorites from Algeria (plus 30 unapproved names) (plus 4 impact craters) |