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Northwest Africa 2997
Basic information Name: Northwest Africa 2997
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 2997
Observed fall: No
Year found: 2006
Country: (Northwest Africa)
Mass:help 43 g
Meteoritical Bulletin:  MB 91  (2007)  Diogenite-unbr
Recommended:  Diogenite    [explanation]

This is 1 of 481 approved meteorites classified as Diogenite.   [show all]
Search for other: Achondrites, Diogenites, and HED achondrites
Comments: Approved 28 Mar 2007
Writeup from MB 91:

Northwest Africa 2997


Find: 2006

Achondrite (diogenite, unbrecciated)

History: A complete stone was purchased in Erfoud, Morocco, in July 2006 and sold to an anonymous buyer in September 2006.

Physical characteristics: A brownish 43 g stone with no remnant fusion crust.

Petrography: (T. Bunch and J. Wittke, NAU) Unbrecciated, cumulate-textured diogenite with well-developed preferred orientation of orthopyroxene grains. Large orthopyroxene oikocrysts (up to 12 mm in longest dimension) surround smaller orthopyroxene grains of similar composition that have long axis deviations from the oikocryst orientation axis. Grain boundaries of all orthopyroxene grains are scalloped to serrated. Sparse, large chromite crystals (up to 2.5 mm) are surrounded in “necklace” fashion by small olivine grains (<0.2 mm) and contain tiny inclusions (<0.03 mm) of aluminous orthopyroxene, diopside, a silica phase, pigeonite, K-feldspar, plagioclase, metal, and FeS. With the exception of feldspars, all of these phases are also found as very small inclusions in host orthopyroxenes.

Mineral compositions and geochemistry: Orthopyroxene (Fs22.1–24.3Wo3.0; FeO/MnO = 29–32); chromite (cr# = 78), “necklace” olivine (Fa21.2–24.5; FeO/MnO = 45–56). Inclusion phases: diopside (Fs10.5Wo41.4), pigeonite (Fs20Wo11.5), K-feldspar (An10.4Or42), plagioclase (An77.6) and metal (Ni = 0.56 wt%).

Classification: Achondrite (unbrecciated cumulate diogenite); minimal shock, minimal weathering. This meteorite is very similar to NWA 4215 in many characteristics, but differs greatly in orthopyroxene grain size.

Type specimen: A 10 g sample and one thin section are on deposit at NAU. The main mass holder is anonymous.

Data from:
  Table 2
  Line 146:
Place of purchase:Erfoud, Morocco
Mass (g):43
Shock stage:minimal
Weathering grade:minimal
Ferrosilite (mol%):22.1-24.3
Classifier:T. Bunch and J. Wittke, NAU
Type spec mass (g):10
Type spec location:NAU
Main mass:anonymous
   and collections
NAU: Geology, Bldg 12 Knoles Dr Northern Arizona University, Flagstaff, AZ 86011, United States; Website (institutional address; updated 12 Apr 2012)
References: Published in Meteoritical Bulletin, no. 91, MAPS 42, 413-466 (2007)
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     This is 1 of 8025 approved meteorites from (Northwest Africa) (plus 1951 unapproved names)

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