A new Spanish meteorite: Retuerta del Bullaque (Ciudad Real). Classification, mineralogy and preservation of the morphology

Abstract

Retuerta del Bullaque is a new Spanish iron meteorite. Found in 1980, has been recovered from the Province of Ciudad Real, near the northern limit of the Cabañeros National Park (39º27’32”N, 4º22’39”W). The specimen is a coarse octahedrite of about 100 kg in weight, with many concave regmaglyphes in one surface and moderate terrestrial weathering. The atmospheric heat-affected rim (≤1.5 mm) is partially preserved. Analysis by ICP-AES (Ni: 7.527 and Co: 0.475 in wt%) and by ICP-MS (Ga: 68.9, Ge: 365, As: 13.7, W: 0.95, Ir: 1.95 and Au: 1.70 in ppm) we used to classify the specimen as an IAB complex (Main Group). Chemically, Retuerta del Bullaque iron is similar to Kaalijarv iron but its mineralogy and texture are more like other low Ni-Au irons of main group (e.g. Diablo Canyon). The bulk of the specimen is a Widmanstätten kamacite (band-width estimated at 2.0 ± 0.3 mm) with large and tabular crystals of cohenite and polygonal kamacite without cohenite that exhibits abundant Neumann lines. Schreibersite (irregular crystals + rhabdite) is rare in the two sectors. Taenite is present in thick lamellae between kamacite bands and pearlitic plessite. Lamellar cohenite is very abundant (9.5% of the total area into two sections 77.7 and 41.1 cm²), is partially covered of schreibersite and contains kamacite-taenite spherules. The larger sections display irregularly shaped troilite-graphite nodules (max. size, 5-12 mm), located in the central areas of the kamacite polygonal sectors. Each nodule has a rim of schreibersite + cohenite. The original morphology of the specimen was preserved making replicas as molds and casts (using elastomers, resins and modified plasters) and a 3D-laser scan.