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Northwest Africa 5515
Basic information Name: Northwest Africa 5515
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 5515
Observed fall: No
Year found: 2007
Country: Algeria
Mass:help 13.7 kg
Meteoritical Bulletin:  MB 96  (2009)  CK4
Recommended:  CK4    [explanation]

This is 1 of 119 approved meteorites classified as CK4.   [show all]
Search for other: Carbonaceous chondrites, Carbonaceous chondrites (equilibrated), CK chondrites, CK chondrites (type 4-6), and CV-CK clan chondrites
Comments: Approved 1 Jun 2009
Writeup from MB 96:

Northwest Africa 5515

Algeria (Coordinates unknown)

Find: Nov. 2007

Carbonaceous chondrite (CK4)

History:  The meteorite was purchased in Munich, Germany in Nov. 2007 from a meteorite seller from Erfoud, Morocco.  The meteorite was claimed by the Moroccan to have been found in Algeria. Over one-half of the stone, weighing 7 kg, was purchased by Michael Farmer. The remaining 6.7 kgs was sold to another meteorite dealer. 

Physical characteristics:  The total mass is 13.7 kgs. It consists of two pieces (7 and 6.7 kgs) that fit together to make a whole stone.

Petrography (T. Mikouchi, UTok): This meteorite shows an equilibrated texture composed of rare scattered chondrules reaching ~1 mm, embedded in fine-grained recrystallized matrix. The grain sizes of matrix minerals are generally several tens of µm. There are abundant irregular-shaped nodules reaching 0.5 mm in size similar to CAI. They are mainly composed of plagioclase and magnetite. Al-rich spinel is nearly absent. The effect of shock metamorphism is minor, but some olivine grains show undulatory extinction.

Mineral compositions and geochemistry: Olivine is equilibrated (Fa29-34). Olivine contains 0.2-0.6 wt% NiO. Pyroxenes are present as low-Ca pyroxene (Fs25-27Wo1) and augite (Fs8-10Wo46-47). Plagioclase composition is heterogeneous ranging An34-72. Magnetite is Cr-rich (Cr2O3 = 5 wt%). Noble gas analysis gives the cosmic-ray exposure ages of T(21Ne)=16 Ma, T(38Ar)=13 Ma and T(3He)=14 Ma (K. Nagao, UTok).

Classification:  Carbonaceous chondrite (CK4); minimal shock, moderate weathering.

Type specimens: A total of 20 g of sample is on deposit at UTok. MFarmer holds the main mass.

Data from:
  Table 2
  Line 55:
Mass (g):13700
Fayalite (mol%):29-34
Ferrosilite (mol%):25-27
Wollastonite (mol%):1
Classifier:T. Mikouchi, UTok
Type spec mass (g):20.0
Type spec location:UTok
Main mass:MFarmer
   and collections
UTok: University Museum, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan (institutional address; updated 3 Oct 2021)
MFarmer: Michael Farmer, P.O. Box 86059, Tucson, AZ 85754-6059, United States; Website (private address)
References: Published in Meteoritical Bulletin, no. 96, MAPS 44, 1355-1397 (2009)
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     This is 1 of 1250 approved meteorites from Algeria (plus 29 unapproved names) (plus 4 impact craters)

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