Denader 004，碳质 CB。 惊艳的基质，包含巨大的铁球粒。 - 1.22 g - (1)

Denader 004 20°08'08.9"N, 4°56'22.8"W

Gao, Mali

分类: Carbonaceous chondrite (CB)

History: The meteorite was found during a search in Mali and subsequently purchased from a local dealer.

Physical characteristics: Several fragments, up to few centimeters in size, with prominently exposed brownish metal nodules in a grayish silicate matrix plus many loose spheres that weathered out.

Petrography: Metal-rich breccia composed of about 40% rounded to ellipsoidal shaped kamacite-dominated metal nodules (apparent diameter 2.5±1.3 mm, n=31) and about 60% silicate groundmass consisting of radial and finely barred chondrules (up to 4 mm in size) plus chondrule and mineral fragments in a fine-grained matrix. Metal nodules are polycrystalline and contain abundant blebby and elongated Cr-bearing troilite inclusions often decorating kamacite grain boundaries. Dominant silicates in chondrules and matrix are enstatite and forsterite with subordinate zoned olivine, ferroan low-Ca pyroxene, and aluminous diopside. Minor phases in the matrix include Cr-bearing spinel, magnetite, troilite, kamacite, taenite, and schreibersite. No refractory inclusions detected. The meteorite is moderately weathered and many metal nodules are surrounded by a thin iron hydroxide rim.

Geochemistry: forsterite: Fa2.7±0.1 (Fa2.7-2.8, n=7); zoned olivine: Fa17.9±2.5 (Fa14.7-22.0, n=7); enstatite: Fs2.0±0.1Wo0.6±0.1 (Fs2.0-2.1Wo0.5-0.6, n=7); ferroan low-Ca pyroxene: Fs19.2±0.1Wo0.6±0.2 (Fs19.1-19.3Wo0.4-1.0, n=7); aluminous diopside: Fs2.4±0.2Wo41.7±0.7 (Fs2.3-2.7Wo40.6-42.5, n=7); kamacite is Si-free and contains 5.95±0.20 wt% Ni, 0.26±0.03 wt% Co, and 0.40±0.02 wt% P, n=7 and troilite inclusions contain up to 5.6 wt% Cr.

Classification: Carbonaceous chondrite (CB). The high abundance of silicate portions (60% vs. less than 50% in CBa and less than 30% in CBb), diameter of chondrules (up to 4 mm vs. cm sized in CBa and 0.2-1 mm in CBb), the presence of fine-grained matrix, and the occurrence of zoned olivine plus ferroan pyroxene does not allow an unambiguous assignment to a known subgroup.

Shock stage: low
Weathering grade: moderate
Classifier: A. Greshake, MNB.

This lot comes with certificate of authenticity.
Thanks for your interest.