CAÇAPAVA DO SUL
BRAZIL - RS
Iron meteorite - Medium Octahedrite IID.
(Zucolotto, M.E., MNRJ, IGEO-UFRJ) The etched sections display a medium Widmanstätten structure, consisting of kamacite lamellae bordered by taenite and plessite fields. The kamacite lamellae are straight, swollen and have an average bandwidth of 0.65±0.15 mm and microhardness HV 325±30. The kamacite has an indistinct ε-structure. Taenite and plessite cover 30-40% per area, mainly as comb and net plessite fields and some with martensitic varieties. The broad taenite lamellae have a mean microhardness HV 500±30. Schreibersite occurs as small blocks or skeletal crystals, mainly enveloped by swathing kamacite broad lamellae. Troilite is very rare as scattered nodules.
Bulk composition (INAA - J.T. Wasson, UCLA) in wt%: Ni = 9.43, Co = 0.66; and in ppm: Cr=90, Cu=307, Ga=70.8, As=4.3, W=2.8, Ir=21.6 and Au=0.56. Presents the highest Ir among IID irons and one of the lowest Au and As values. (EPMA - A. Tosi, LABSONDA/IGEO-UFRJ) kamacite 7.32 ± 0.15 wt.% Ni and 0.65 ± 0.06 % Co content and taenite lamellae 21.5±0.5 wt.% Ni and 0.35±0.05 wt.% Co.
Iron (IID), Medium Cctahedrite
J. T. Wasson, M. E. Zucolotto and A. A. Tosi
The meteorite was found around 1908 among the remains of an abandoned country seat. The stone drew attention due to its weight and the farmer decided to use it to amuse visitors. Prof. Elver Ubirajara had heard about the mysterious rock since he was a boy. Recently, thinking it to be a meteorite, he spent many years in finding the current owner of the stone, Mr. João A. R. Lopes. When the meteoritic nature was confirmed by the MNRJ/UFRJ, it was donated to the local university (UNIPAMPA).
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