Rare Plessitic Octahedrite (Limited Supply!)

Stunning NEW Saharan Iron-NWA 2428! John Wasson has described this iron as a IAB sHL, plessitic octahedrite. This exceptional little iron is new, and particularily beautiful iron from the Saharan desert of north-west Africa. There is only one specimen of this meteorite known to exist. It has a brilliant micro-etch pattern which shimmers like thousands of tiny diamonds when moved in the light. This iron also exhibites an interesting heat altered zone of several mm around its exterior. This is a really bizzare etch and we have not see any other iron like it. UCLA originally thought that it was a IIC. It has been classified by Professor John Wasson as a member of the IAB subclass HL. The H stands for High gold content and the L for low nickel content (see Wasson & Kallemeyn, 2002). According to Wasson & Kallemeyn (2002) there are only 8 irons belonging to this IAB subgroup. Saharan irons are rare and this one is particularly rare with a total known weight prior to cutting of just 1650 grams. After accounting for the 55 grams donated to Science as type specimens and cutting losses, there will only be about 1200 grams of this iron left, and we are the sole suppliers. This gorgeous iron has a nickel content of 11.8%. Each of the specimens offered below was expertly prepared. The Final elemental composition, as determined by UCLA: Cr 22 µg/g, Co 5.58 mg/g, Ni 117.7 mg/g, Cu 200 µg/g, Ga 16.8 µg/g, As 28.3 µg/g, Sb 180 ng/g, W 0.17 µg/g, Ir 1.09 µg/g, Au 2.646 µg/g.

John Wasson has described this iron as a IAB sHL, plessitic octahedrite. His description is below:

This small iron from J. Birdsell has long (to 2 cm) schreibersite lamellae surrounded by thick (0.6 mm) swathing kamacite; these comprise about 20% of the area. The intermediate regions can be characterized as plessitic octahedrite, but alteration makes the pattern indistinct. Following the precipitation of the schreibersite, the swathing kamacite and the plessitic region impact produced sheare has fractured the meteorite adjacent to the schreibersite lamellae. In some cases the shear crosses the lamellae to produce en echelon faults. Post shock annealing has resulting in recrystallization of large (~5 mm) patches of the swathing kamacite with the result that these preferentially reflect oblique light with different intensities. There is a relatively thick (1-2 mm) reheated zone around the meteorite. Weathering is minor. See photo. JTW May 2005