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Northwest Africa 12272
Basic information Name: Northwest Africa 12272
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 12272
Observed fall: No
Year found: 2017
Country: (Northwest Africa)
Mass:help 153 g
Classification
  history:
Recommended:  LL7    [explanation]

This is 1 of 55 approved meteorites classified as LL7.   [show all]
Search for other: LL chondrites, LL chondrites (type 4-7), Ordinary chondrites, and Ordinary chondrites (type 4-7)
Comments: Approved 2 Dec 2018
Writeuphelp
Writeup from MB 107:

Northwest Africa 12272 (NWA 12272)

(Northwest Africa)

Purchased: 2017 Oct

Classification: Ordinary chondrite (LL7)

Petrography: (K. Metzler, IfP) Unbrecciated ordinary chondrite with distinct recrystallization texture. Large areas of secondary feldspar grains (many with sizes >100 µm) which poikilitically enclose olivine and pyroxene grains. Many plagioclase grains with rectangular outlines due to the alignement along boundaries of recrystallized pyroxene crystals. Some metal veins up to 4 mm are observed. The outlines of a few large chondrules are still dimly visible.

Geochemistry: Mineral compositions and geochemistry: The mean olivine composition is Fa29.9±0.3 (29.1-30.5); n=14. The mean low-Ca pyroxene composition is Fs23.9±0.4Wo4.1±0.3 (Fs23.3-24.4Wo3.6-4.5), n=14; Mean CaO concentration in low-Ca pyroxene: 2.1±0.2 (1.9-2.3) wt%. The mean composition of Ca-rich pyroxene is Fs12.8±0.9Wo38.5±1.9 (Fs10.8-13.9Wo36.7-41.9), n=16.

Classification: LL chondrite based on mineral chemistry. Petrologic type 7 based on the equilibrated state of olivine and pyroxene, and large grain size of secondary plagioclase.  According to Tait et al. (2014) the transition between types 6 and 7 is a CaO concentration in low-Ca pyroxene of 1.0 wt%; in this sample the respective value is 2.1 wt%. According to Brearley and Jones (1998) Ca-rich pyroxene in type 6 chondrites has a Wo value of 45 mol%, which decreases in type 7 chondrites to 45-36 mol%. In this sample the respective value is 38.5 mol%.

Bibliography:
  • Brearley A.J. and Jones R.H. (1998) Chondritic meteorites. in Planetary Materials, Reviews in Mineralogy v. 36, J.J. Papike Ed., Mineralogical Society of America, 3-398. ISBN 0-939950-46-4; ISBN13 978-0-939950-46-1 (link)
  • Tait A.W., Tomkins A.G., Gode B.M., Wilson S.A., Wilson, and Hasalova P. (2014) Investigation of the H7 ordinary chondrite, Watson 012: Implications for recognition and classification of Type 7 meteorites. Geochim. Cosmochim. Acta 134 175-196. (link)
Data from:
  MB107
  Table 0
  Line 0:
Place of purchase:Guelmim, Morocco
Date:P 2017 Oct
Mass (g):153
Pieces:1
Class:LL7
Shock stage:S2
Weathering grade:W2
Fayalite (mol%):29.9±0.3
Ferrosilite (mol%):23.9±0.4; 12.8±0.9
Wollastonite (mol%):4.1±0.3; 38.5±1.9
Classifier:K. Metzler, IfP
Type spec mass (g):20
Type spec location:IfP
Main mass:Nourddine Azelmat, Morocco
Comments:Submitted by K. Metzler, IfP
Institutions
   and collections
IfP: Institut für Planetologie, Wilhelm-Klemm-Str. 10, 48149 Münster, Germany (institutional address; updated 23 Jan 2012)
Catalogs:
References: Published in Meteoritical Bulletin, no. 107, in preparation (2018)
Find references in NASA ADS:
Find references in Google Scholar:
Photos:
CreditPhotos
Public domain photographs:
Knut Metzler      
Geography: 
Coordinates:Unknown.

Statistics:
     This is 1 of 6551 approved meteorites from (Northwest Africa) (plus 2022 unapproved names)

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