A large 4.5cm crystal composed of thin foliated sheets of soft blueish-silver Molybdenite partially exposed in white very course crystalline Albite-Anorthite matrix with large green Diopside crystals. According to info on Mindat.org's page for the American Moly. Mine the mineralization occurs in a Pyroxenite at the contact of a Granite and a Limestone, or more commonly referred to as a skarn.