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A preliminary report of the Chisenga iron meteorite, Malawi

1991; Elsevier BV; Volume: 12; Issue: 4 Linguagem: Inglês

10.1016/0899-5362(91)90013-o

0899-5362

L.S. Chapola,

Planetary Science and Exploration

An iron meteorite fell on the afternoon of 17th January, 1988, in the Chisenga area, Chitipa district (10° 03′ 34″ S,33° 23′ 42″ E). The meteorite was immediately recovered. It is a triangular body 16 cm high and 15 cm on its base. The meteorite weighed 3.92 kg on recovery. Its surface has spectacular smooth thumb print-like depressions and is entirely covered by a black fusion crust. Chemical analysis has indicated 92.6% Fe, 6.2% Ni, 0.6% Co, 139 ppm Cr, 136 ppm Ag, 68 ppm Zn, 0.1 ppm Au, 0 ppm Pb, As and S. The meteorite crystallised as two phase kamacite and taenite. The Widmanstatten structure is composed of 1.5 mm wide kamacite bands and about 0.1 mm taenite bands. Nickel content indicates that the meteorite is close to Group IA and IIB of the chemical groups, while texture indicates that it is a coarse octahedrite. Shock before descending to earth and impact in flight and on landing resulted in fracturing. Terrestrial corrosion has attacked some of the nickel rich taenite-plessite bands.