Castenaso meteorite, Castenaso, Metropolitan City of Bologna, Emilia-Romagna, Italyi

Regional Level Types
Castenaso meteorite	Meteorite Fall Location (Uncertain)
Castenaso	Municipality
Metropolitan City of Bologna	Metropolitan City
Emilia-Romagna	Region
Italy	Country

NOTE: Folco et al. (2007) showed that the meteorite is actually from a desert (probably the Sahara) and concluded "The Italian name “Castenaso” should be discarded and substituted with an appropriate name for meteorites of uncertain origin like the ones from the Nova series."

Official name: Castenaso
Observed fall: no
Reported find: 2003, July 15
Coordinates (The Meteoritical Bulletin): 44°29'42N, 11°21'20"E [The reported longitude is wrong! 21' appears to be a typo for 27'. The correct one should be 11°27'20"E]
Recovered weight: 120 g
Ordinary chondrite, type L5

The amateur naturalist Franco Merighi reported to Romano Serra, curator of the Osservatorio Astronomico e Museo "G. Abetti" (OAM) at San Giovanni in Persiceto, Bologna, that he found the stone sitting on the sandy soil of the right bank of the Idice stream, near the Casalunga Golf Club, on July 15, 2003 (Serra & Chinellato, 2003). Based on petrographic observations carried out on three polished thin sections made available by OAM, which acquired the specimen, the Castenaso stone has been classified as an L5, slightly weathered (W1), ordinary chondrite (Russel et al., 2005).

At first glance, however, the stone looked suspicious because it resembled a weathered hot-desert chondrite with a partially oxidised and polished fusion crust. In addition, further observations under the stereomicroscope revealed that the specimen had been carefully cleaned, with apparent removal of soil from the few fractures present on its external surface. Nevertheless, by upturning one deep fracture, some residue of the original soil filling the cracks was found. The remaining soil turned out to be mainly composed of rounded, millimeter-size quartz grains. The morphology of the quartz grains, which is typical of eolian environments, is anomalous for a meteorite found in a fluvial environment. Because of these apparent anomalies, a forensic study aimed to authenticate its recovery location has been carried out (Folco et al., 2007). Inductively coupled plasma–mass spectrometry (ICP-MS) data reveal that Castenaso is significantly enriched in Sr, Ba, Tl, and U, and suggest geochemical alteration in a hot-desert environment. The alteration is minor: Castenaso is not coated by desert varnish and does not show significant light rare earth element (LREE) enrichment or loss of Ni and Co. The apparent contrast in size, morphology, and composition between the soil particles filling the external fractures of Castenaso and those from the bank of the Idice stream observed under the scanning electron microscope (SEM) suggests that Castenaso did not reside at the reported find location. Abraded quartz grains (up to 1 mm in size) in Castenaso appear to be undoubtedly from a hot-desert eolian environment: they are well-rounded and show external surfaces characterised by the presence of dish-shaped concavities and upturned silica plates that have been subject to solution-precipitation and subsequent smoothing. These authors therefore concluded that Castenaso is one of the many hot-desert ordinary chondrite finds, probably from the Sahara, currently available on the market.

Other Regions, Features and Areas containing this locality

References