Solid solutions in the Epidote group of minerals: Pb and REE rich Piemontite from Nezilovo, Macedonia

An unusual Pb- and REE-rich epidote group mineral , related to piemontite was found near Nezilovo, Macedonia, within a micaschist complex in the upper part of the Babuna river, ca 40 km southwest of Skopje. The rock contains red mica, quartz, ardennite, gahnite and piemontite. The piemontite from Nezilovo is deep red in colour, almost black, with an adamantine luster and greyish-pink streak. It is brittle, with an uneven fracture and with no observable cleavage. The crystals often show twinning parallel to 100 and in this case display sections of isometric shape. Monocrystals are flattened in 001 and elongated parallel to b. They are optically negative, the refractive indices being around 1.8. The optical orientation is similar to that of allanite.