Northwest Africa 2965
Algeria
Find: August 2005
Enstatite chondrite (EL 6/7)
History: Hundreds of fragments that weigh >100
kg were collected in the Algerian desert in 2004. Small fragments (~100 g)
are commonly weathered to a dark brown with very dark weathering veins.
Large pieces may retain portions of weathered fusion crust with only
moderate to lightly weathered interiors. Petrography: (T. Bunch and
J. Wittke. NAU) A completely recrystallized enstatite chondrite with
polygonal to irregular grain outlines. The grain size varies from 0.02 mm to
0.7 mm. Round, curved, blocky objects contain coarser-grained orthopyroxene
than in the matrix. No relict chondrules, sensu stricto, were
observed in ~32 cm2 that were analyzed. Metal, daubreelite, and
tiny, vermicular grains of graphite are also present and constitute < 3 vol%.
Geochemistry: Orthopyroxene (Fs98.4
± 0.02), plagioclase (An17.8Or4.4),
troilite with Ti = 0.91, Cr = 1.10, Zn = 0.6 (all wt. %). Classification:
Enstatite Chondrite EL 6/7. It has absolutely no evidence of chondrules.
Low-level shock, the weathering grade ranges from W2-W5. Specimens: A
24 g sample is on deposit at NAU. Turecki/Reed hold the main mass.
Price $2/g over 1kg $1.25/g examples below
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