Alkaline Potassic Volcanites In Roman Soils; Silent Witnesses In An Organized Crime Case.

During the Nineties a criminal group, which claimed the paternity of Red Brigades in action in the Seventies, committed a series of violent crimes, including armed robbery, terrorist outrages and homicides with a political background. At the end of the decade the investigators arrested the group members.

During a judicial site survey in one of the group den in Rome, the Forensic Science operators found gardening tools and a pair of hiking shoes with soils. The investigators supposed the criminals had hidden fire-arms and explosives. Therefore, they requested Forensic Geologists to carry out a comparison between the soil found on the shoes and the tools and the soil samples collected at several sites linked to the criminal group members.

The comparison didn’t provide any useful information, as the reference soils didn’t have any meaningful analogies with the comparison soils. Nevertheless, a deep mineralogical and petrographic analyses of numerous lava particles in the soils collected at the den in Rome, allowed geologists to infer that those soils were likely to come from volcanic alkaline-potassic deposits of the Roman Comagmatic Province. In particular, the total absence of mineral sanidine in those soils, both as singular particles and as phenocrysts in the lavas, supplied further indications on their probable origin. Indeed, the sanidine is widely present in the volcanic deposits of the Sabatine Volcano District, which spread throughout the Rome northern area, while it isn’t present in the volcanites of the Alban Hill Volcano District, deposited in Rome southern area.

The accurate mineralogical and petrographic analyses of volcanic particles in reference soils, supported by a scrupulous geological study of the territory, allowed to delimit a wide but well-defined area, in which the investigators carried out further inquiries and found new evidences linked to the criminal group.