Northwest Africa 7441 (NWA 7441)

(Northwest Africa)

Purchased: 2004

Classification: Ordinary chondrite (LL3.4)

Physical characteristics: Black fusion crust is mostly weathered away but is well preserved on one of the faces.

Petrography: (K. Guo, ROM): Chondrules are clearly defined on the cut surface, including a few white-colored chondrules >5 mm. One large 16 mm porphyritic chondrule with a white rim was present. The chondrules have an average diameter of 0.77±0.48 mm (N=50) and make up 75% of the thin section. Zoning of olivine is common. Troilite and silicate inclusions are common in metals. Matrix light-brown to black. Glass in the matrix appears ruby in both plain and crossed polarized light. In cathodoluminescnece (CL), the matrix is almost all nonluminescent with a few scattered areas emitting red CL. Chondrule mesostasis is non-luminescent (30%), emits dull red-blue (10%) or bright blue (60%) CL. Red CL in chondrule olivine is present but constitutes less than 10% of the areas. Olivine primarily shows sharp extinction. About 50% of the sulfides are replaced by iron oxides.

Geochemistry: Olivine Fa_20.2±11.1 (N=17), low-Ca pyroxene Fs11.5±6.2 Fs_11.5En₈₇Wo₂ (N=28), and high-Ca pyroxene Fs_20.6±20.0En₆₂Wo₁₇ (N=2); PMD FeO olivine=45.6 and PMD FeO low-Ca pyroxene=46.6; σ-Cr₂O₃=0.11 wt%, mean Cr₂O₃=0.06 wt%.

Classification: Ordinary chondrite LL3.4, S1, W2

Specimens: A total of 340.18 g is on deposit at ROM.