NWA 7402 L3.1 Chondrite Meteorites for Sale

Location: Northwest Africa, exact location unknown.
Found: 2010, purchased on August 26, 2010, by Eric Twelker from a meteorite trader in Morocco.
Type: Ordinary chondrite (L3.1).

Description: Physical characteristics: A 4013.4 g individual stone, with fusion crust intact and partially rusted. Rust-colored, apparently weathered areas with orange-brown chondrules surround less-weathered regions containing light-gray chondrules set within a darker gray groundmass. The meteorite is a breccia, with occasional clasts of different lithologies present (up to ~5 mm width). The transition from weathered to unweathered lithology is abrupt, and does not correlate with clast boundaries. Petrography: (C. E. Jilly-Rehak, UH) Transmitted and reflected light optical microscopy reveal a high abundance of chondrules embedded in a clastic, sulfide-rich matrix. Chondrules range from ~0.2 - 2 mm in apparent diameter, and an anomalously large barred olivine chondrule of 8 mm exists in one thin section. Chondrule types found in the meteorite include porphyritic olivine, barred olivine, porphyritic pyroxene, radial pyroxene, and cryptocrystalline. The porphyritic olivine chondrules comprise both type I (Fa<2) and type II (Fa_10-25). Fine-grained FeO-rich silicate rims are observed surrounding some (but not all) chondrules. The rims are typically embedded with μm-sized Fe sulfides. The matrix contains abundant Fe,Ni metal and sulfides, as well as chondrule fragments and isolated silicate grains. Large opaque assemblages (~300 μm in diameter) are found in the matrix, containing both kamacite and taenite, Fe sulfides, and Fe oxides. Optical microscopy reveals moderate shock and weathering, corresponding to maximum stages S2 and W2, respectively. The studied sections do not contain any calcium-aluminum inclusions (CAIs), although one aluminous chondrule was found. The pre-weathering metal abundance could have been up to 10.7 wt%, placing the meteorite in the L-chondrite range, also in agreement with the magnetic susceptibility. Geochemistry: Olivine is highly variable in composition, ranging from Fa<1 to Fa₃₆ (mean, Fa_12.9±8.7, N=102). Low-Ca pyroxene is Fs_8.4±7.6 (N=71). Cr₂O₃ in 140 ferroan olivine grains is = 0.41±0.13 wt.%. Separated matrix material (<50 mg) was measured via Raman spectroscopy; peak intensities (I) for the D and G bands have FWHM=181±16 and ID/IG=0.93±0.04. Classification: Ordinary chondrite (L3.1-anom), S2, W2. It is possibly paired with NWA 5717. Raman spectroscopy of organic matter in the fine-grained matrix indicates that the sample is petrologic type 3.1, plotting within analytical error of Bishunpur. EPMA of chromium contents in olivine shows that NWA 7402 lies between types 3.00 and 3.15, but anomalously falls off the trend for typical UOCs in Grossman and Brearley (2005). However, analyses of control specimens Semarkona and Bishunpur generally agree with the literature values. Furthermore, NWA 7402 has an elevated sulfide abundance (>15 wt%).
Link to NWA 7402 in the Meteoritical Bulletin Database.
Petrography and classification of NWA 7402: A new sulfide-rich unequilibrated ordinary chondrite