Barbianello meteorite, Barbianello, Pavia Province, Lombardy, Italyi

Regional Level Types
Barbianello meteorite	Meteorite Fall Location
Barbianello	Commune
Pavia Province	Province
Lombardy	Region
Italy	- not defined -

Official name: Barbianello
Observed fall: no
Find: October 1960 or 1961
Coordinates (Catalogue of Meteorites): 45°3'28"N, 9°11'44"E
Approx. recovered weight: 860 g
Iron ungrouped (ataxite)

A single mass of 860 g was found in October 1960 (or 1961) by the farmer Clemente Allini while he was ploughing a cornfield in the locality Antoniana Piccola (Barbianello municipality; 45°03’28’’N 9°11′44′′E). In 1972, the young Carla Allini showed it to her teacher, who submitted it to Professor G. Giuseppetti at the University of Pavia. Based upon a visual examination and preliminary bulk analyses carried out in 1974 (using atomic absorption spectroscopy [AAS] and traditional wet methods), it was identified as an unusually Ni-rich iron meteorite.

Classification and mineralogy: ataxitic texture, lacking Widmannstätten patterns; severely altered surface, but fresh interior showing dark and light regions texturally similar to, but compositionally distinct from, Santa Catharina iron meteorite. Light regions are mainly composed of taenite (Ni 27 wt%) with quantitatively subordinate kamacite (Ni 5.4 wt%), often nucleated around "schreibersite" (now identified as allabogdanite; Britvin et al., 2019). Dark regions are inhomogeneous with Ni 40–58 wt% and up to 20% oxygen (calculated); relics of metal with Ni3Fe (awaruite) composition are present. The search for troilite, graphite or silicate mineral, carried out on two distinct polished mounts with both optical and electron microscope was negative in both light and dark areas. Bulk metal composition (instrumental neutron activation analysis [INAA], Max-Planck-Institut für Chemie, Mainz): Ni = 27.1 wt%; Co = 5480 µg/g; Cu = 1380 µg/g; Ge = 73 µg/g; Ga = 28 µg/g; As = 16.6 µg/g; Pt = 1.6 µg/g; Ir = 1.51 µg/g; Os = 1.4 µg/g; Au = 1.39 µg/g. Based on its Ge/Ga ratio, composition falls into the IAB-IIICD trend; concentrations of Ga (28 ppm) and Ge (73 ppm) are higher than in typical IAB-IIICDs, yet comparable to concentrations in the Ni-rich IABs San Cristobal and Yamato as well as the ungrouped iron Elephant Moraine. However, the distinctly lower than IAB-IIICD As (16.6 ppm) and Au (1.39 ppm) contents allows to classify this iron as chemically ungrouped. This meteorite, although similar to IAB-IIICDs, is actually unique, and is classified as an ungrouped ataxite (Fioretti & Zipfel, 2004).

Specimens: the main mass (479 g) is preserved at the Municipal Natural History Museum of Milano (Inventory number: MSNM-M-31767).

Phosphides in Barbianello meteorite were described as schreibersite, but in fact are represented by its nickel-dominant analogue, nickelphosphide, (Ni,Fe)3P (Britvin et al., 2019).

Other Regions, Features and Areas containing this locality

References