Name: Larkman Nunatak 04315 This is an OFFICIAL meteorite name. Abbreviation: LAR 04315 Observed fall: No Year found: 2003 Country: Antarctica [Collected by US Antarctic Search for Meteorites program (ANSMET)] Mass: 1165 g
Macroscopic Description: Kathleen McBride
Dark brown/black patchy fusion crust covers 65% of the exterior. Exposed interior is dark in color with lighter inclusions. The interior is dark, ultramafic with a few light inclusions. This hard meteorite is rusty and has a coarse grained texture. Weathering is more extensive near the exterior.
Thin Section (,7) Description: Tim McCoy
The section consists of an aggregate of large olivine and pyroxene grains up to 2 mm across. Olivine grains are rimmed by carbon-rich material containing traces of metal. While these metal-bearing rims appear to define individual olivine crystals, those crystals exhibit subdomains a few hundred microns across in transmitted light and no reduction is observed between the subdomains. Olivine has cores of Fa19, with rims reduced to Fa2. Metal and sulfide form veins between the olivines, with metal often forming rounded blebs within the sulfide. The pyroxene grains are dominantly pigeonite (Fs7-9Wo7-9) and exhibit a wormy texture with elongate and irregular voids (graphite-filled?), and inclusions of metal and sulfide (sometimes associated with the voids). Within the pigeonites, but distinct from the voids, are found inclusions of subcalcic augite (Fs7-9Wo24-28) and, in association, an apparently non-stoichiometric phase highly enriched in SiO2, and contains Al2O3. The meteorite is an anomalous ureilite.
Oxygen isotope analysis - J. Farquhar: δ18O = 7.2 per mil; Δ17O = -0.8 per mil