Cinnabar and other high-density minerals from stream sediments of Monti Pisani (Pisa and Lucca provinces, Tuscany)

We describe the results of a stream sediments survey carried out in the Monti Pisani area (Pisa and Lucca provinces, Tuscany). The survey was initially aimed at locating the primary source of cinnabar (HgS) frequently found as crystal fragments in many streams of Monti Pisani. The search lead to the discovery of a small outcrop of phyllitic rocks characterized by an intense low-temperature hydrothermal alteration (kaolinite-halloysite±illite) and by a diffuse, low-grade cinnabar min- eralization. As a by-product of this survey we recovered many different types of high-density (> 3.0 g/cm 3) minerals. These latter are sourced in the Triassic meta-siliciclastic rocks of the “Verrucano” and “Quar- ziti di Monte Serra” Fms (e.g., garnets, kyanite, staurolite, sillimanite, tourmaline, zircon, Na-amphibole, etc.) and in the sin- and post-Al- pine veins and other mineralizations related to hydrothermal activity of variable nature and age (e.g., cinnabar, pyrite, hematite, sphalerite, tourmaline, etc.). Several grains of native gold larger than 100 μm have been also found. Finally, the recovery of several crystal fragments of SiC is quite intriguing and deserves further more specific analyses in order to ascertain their natural or anthropogenic origin.