Castiglione del Lago        43.129°N, 12.02317°E

Umbria, Italy

Find: 1970

Classification: Iron meteorite (IAB-MG)

History: A single mass, weighing 667 g, was recovered in 1970 near Castiglion del Lago by a peasant while plowing his field. The peasant preserved the sample for many years in his home considering it just a curiosity until he read an interview of Matteo Chinellato, an Italian meteorite collector, in 2007 who invited people to send him potential meteorites for analysis. Chinellato received the main mass, cut a slice and sent it to MSP and to MSN-Fi for analysis.

Physical characteristics: The main mass has a severely rusted outer surface and has been cut on one side to get the type specimen. An etching of the cut surface showed a distinct Widmanstaetten pattern.

Petrography: (V. Moggi Cecchi, G. Pratesi, S. Caporali, Uni-Fi). Although silicate inclusions are visible on the cut and etched type specimen, the 1 × 1 cm polished section examined does not contain silicates. Metal is formed by coarse-grained (~4 mm width) equigranular kamacite grains with 120° grain boundaries, inside which Neumann lines are visible. Taenite is rare. Scattered schreibersite laths, up to 100 microns in width and to 1 mm in length, can be observed within some kamacite grains and at grain boundaries, frequently surrounded by iron oxides.

Geochemistry: SEM-EDX spot analyses, all in wt% (V. Moggi Cecchi, G. Pratesi, S. Caporali, Uni-Fi): schreibersite P_15.5±0.2Fe_47.0±0.3Ni_37.5±0.4 (N=5); taenite Fe_75.4±0.5Ni_24.6±0.2 (N=5) ; kamacite Fe_93.5±0.6Ni_6.5±0.2 (N=7). Bulk composition (C. Herd and G. Chen, UAb) Ni=66.4, Co=4.4 (both mg/g); Cu=151, Ga=98.2, Ge=414, W=1.4, Ir=4.2, Pt=8.1, Pd=3.5, Ru=7.0, Re=0.3, Os=1.4, Ag=1.6, Sb=0.5 (all ?g/g). Obtained by ICP-MS using North Chile as a calibration standard.

Classification: Iron meteorite, IAB-MG, coarse octahedrite. Composition is consistent with IAB Complex, Main Group (MG).

Specimens: An end-cut, weighing 27.2 g, is on deposit at MSP (inventory number MSP2391). A polished thin section is on deposit at MSN-Fi. Main mass with Matteo Chinellato.