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The mid-infrared spectra (4000-500 cm-1, i.e., 2.5-20 micron) of 27 stones
from the Almahata Sitta meteorite
fall are presented. Samples were prepared as standard KBr pellets with a
1:100 ratio of meteorite to KBr;
typical meteorite samples were ~1-3 mg. Spectral profiles are dominated
by a 10 micron SiO adsorption
feature indicative of pyroxenes and olivines. These data are largely
consistent with previous measurements
of ureilites at these wavelengths [1]. The ratio of olivine to pyroxene
varies from one stone to the next, and
even between multiple samples of the same stone in some instances.
Almahata Sitta has been classified as
an anomalous polymict ureilite based on the extensive initial studies of
a few meteorite fragments [2]. The
spectra presented support this assessment and provide further insight
into the bulk mineral composition of
the meteorite.
References: [1] Sandford, S.A. (1993) Meteoritics 28, 579-585; [2]
Jenniskens et al. (2009) Nature 458,
485-488.
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