An Attractive Blue Diopside from Sissone Valley, Western Alps, Italy

In this work a rare and attractive blue diopside present in Sissone valley the Western Alps was investigated through different methodologies: geological survey; standard gemological methods; X-Ray Powder Diffraction; SEM observations; Raman spectrometry; EMP analyses of major elements; LA-ICP-MS for minor trace elements. The host rock gems is represented by Mg-calcite bearing marble, belonging to Suretta nappe composed diopside, lizardite, phlogopite, forsterite, Ca-Mg-amphibole, thomsonite; metamorphosed intrusion Masino-Bregaglia pluton. generally found core veins contact with green–blue tremolite and, more externally, green–yellowish lizardite. samples show opaque diaphaneity, are inert long short-waves UV radiation, their specific density varies between 3.24 3.30 g/cm3 while medium refraction 1.680–1.683. shows polycrystalline texture interstitial which acts as binder. characteristic blue–turquoise color mainly determined traces V subordinately Fe, Mn, Cr Ti. contents Ti good positive correlation. minerals associated lenticular also enrichments V. could certainly commercial value, but unfortunately it difficult reach outcrop sites.