gems, jade, amphibole jade, nephrite, Italy, Mastabia, Val Malenco

At Mastabia in Val Malenco, northern Italy, a major deposit of nephrite jade was recently identified at the site of an abandoned talc mine. Geologically, the talc orebody consists of steeply dipping lenses associated with a fault wedge of dolomitic marble and calc-silicate rocks of Triassic age. The nephrite jade is hosted within massive tremolitite at the core of the talc orebody, and both the nephrite and tremolitite were previously discarded as waste during talc mining. Recovery of nephrite from spoil heaps is now underway. The jade displays uneven pale green to yellow-green hues, with grain size ranging from fine- to coarse-grained. Accessory minerals include calcite, talc, and opaque iron minerals. Classified as para-nephrite, the jade formed alongside talc and tremolitite through intense hydrothermal alteration and decarbonation of dolomitic marble along shear zones associated with thrust structures. While the total quantity of nephrite remains uncertain, it appears substantial, and the material is currently being fashioned into various jewellery and ornamental items.