Northwest
Africa 4422
~32°16'N, ~3°28'W
Morocco
Find: May 2006
Carbonaceous chondrite (CK4)
History: P. Thomas purchased one stone reportedly from
Beni Tajjite, province of Figuig, Morocco, in May 2006.
Physical characteristics: One complete, pyramid-shaped
stone weighing 147.72 g, entirely covered with a very black
fusion crust; the crust is very thin on one face.
Petrography: (M. Bourot-Denise, MNHNP) Chondrule and CAI
dimensions are between 500 and 1000 µm; CAIs are
relatively abundant. Magnetite is the most abundant opaque;
it rims chondrules and CAIs, makes up big nodules in association
with sulfide, or is scattered as small angular grains in
matrix and chondrule rims. Matrix is completely recrystallized.
BSE images show that all silicates are equilibrated, even
though the chondritic texture is well preserved. The polished
section studied contains a 3000µm diameter chondrule
whose core of pyroxene laths is surrounded by a double
rim peppered with small magnetites.
Geochemistry: Olivine and low-Ca pyroxene are homogeneous,
mean Fa = 30.2 ± 0.3, mean Fs = 26.00 ± 0.25.
Magnetite, Cr2O3 = 3.79, MgO = 0.16 (both in wt%), in the
equilibrated CK domain. Plagioclase, An in the range 34.8-72.3.
Magnetic susceptibility: (J. Gattacceca, CEREGE) = logc
= 4.93 10-9 m3/kg.
Classification: Carbonaceous chondrite (CK4); minimal shock,
moderate weathering.
Type specimens: A total of 21.4 g of sample (1 sawn fragment
with crust) and one polished mount are on deposit at MNHNP.
Thomas holds the main mass.
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