The Debated Discovery of Dolomite and the Proposal of a New Geosite at Borcola Pass (Eastern Italian Pre-Alps) in Honor of Giovanni Arduino

Abstract

Within the Venetian Pre-Alps, the Borcola Pass connects the Posina (Vicenza province) and the Terragnolo (Trento province) valleys. The Posina valley is located north of Schio (Vicenza) within the Italian Southern Alps structural unit. In this area, the injection of Paleogene basaltic dykes along fault/fractures in the late Triassic Dolomia Principale unit has produced a local metamorphism of the dolomite rock into a marble characterized by the presence of brucite veins. This marble was studied in the eighteenth century by the famous Italian scientist Giovanni Arduino, who understood its metamorphic origin. In fact, the marble is always associated with sub-vertical basaltic dykes intruded into the carbonate rocks of the Pre-Alps. Arduino performed also chemical experiments on the marble. The reading of the description of the experiments induced later authors (e.g., Maraschini, von Morlot, Mc Kenzie) to infer that Arduino unknowingly discovered the mineral called dolomite. In this work, we propose that the abandoned Borcola Quarry should be nominated as a geosite, to allow its conservation and popularization and to preserve the memory of a probably minor, yet informative step in the long-lived history of the discovery of dolomite. In addition, this site presents other reasons of interest, such as petrography, mineralogy, structural geology, industrial archeology, and eco-geotourism. The proposed geosite is therefore of great importance in terms of its multidisciplinary scientific value, aesthetic appeal, and educational value.