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546 gram slice. 230 x 130 x 3 mm.   Iron, IIF

TKW 60.5 kg. Fall not observed. Found January 2018, North-Eastern, Kenya.

1 of only 7 meteorites with this classification, as of today.


 

Randy writes:

When I saw this slice of Balambala for sale, I couldn't pass it up. It has the most interesting etch pattern in my collection.

Balambala was found in 2018 in Kenya. Met Bul says it was a single 60.5 kg mass (see photo 1 courtesy Mark Lyon) but was apparently not handled well when it was found (poor initial cutting).

From the MetBul:

History: Dhagax Bir is the name attributed to the meteorite by the region’s goat herders; the name means metal stone in the local spoken Somali dialect. According to the local residents the meteorite was in this location for as long as anyone could remember, including a woman 60 years of age who regularly herded goats past this stone since she was 10 years old. In January 2018, a nomad identified the stone as an iron meteorite, and then brought it to a local broker in the nearest city of Garissa. The broker began circulating photos and it was subsequently purchased by Mahamed Nur Ogle and John Higgins.

Physical characteristics: The single, approximately shield-shaped mass is about 33 × 41 cm in width and 10-15 cm thick. It is covered in large (~5 cm-wide) regmaglypts; a few cm-sized spherical holes are also present on one side. Some rust is present on the top surface, but otherwise, there is little evidence of oxidation.

Petrography: (C. Herd and L. Tunney, UAb) Optical investigation of a 4.5 × 6 cm polished and etched end slice reveals cm-scale rounded troilite inclusions, and lath-like (~1 × 8 mm) schreibersite inclusions, both swathed in kamacite. The bulk of the meteorite consists of kamacite spindles in a matrix of taenite. The spindles occur evenly throughout, except for adjacent to inclusions, where ~500 μm-wide spindle-poor regions are surrounded by ~200 μm-wide spindle-rich rings that broadly parallel the outlines of the inclusions. SEM investigation reveals that larger kamacite spindles or groupings of spindles are often cored by 50-100 μm subequant schreibersite crystals. The average kamacite bandwidth is 53±17 μm (n=36). Taenite is zoned to higher Ni adjacent to kamacite spindles. No alteration was observed.

Geochemistry: (C. Herd, L. Tunney, and G. Chen, UAb) ICP-MS data, using sample of North Chile (Filomena) as standard: Ni = 13.0, Co = 0.67 (both wt%); Ir = 5.2, Ge = 223, Ga = 8.1, As = 20.6, W = 0.76, Re = 0.45, Pt = 14.9, Cu = 208, Au = 2.6 (all µg/g).

Classification: Iron, IIF, based on the high Ge/Ga ratio, high Co content, and fit with regression parameters established by Kracher et al. (1980).