Piemontite-(Pb), CaPbAI_2Mn~(3+) [Si_2O_7][SiO_4]O(OH), a new mineral species of the epidote supergroup

摘要

The new epidote-supergroup mineral piemontite-(Pb), the Pb-dominant analogue of piemontite, was discovered in the "Mixed Series" formation, near Nezilovo village, Jacupica Mountains, Macedonia. Associated minerals are barite, dolomite, cal-cite, hematite, Zn- and Mn-bearing phlogopite, hedyphane, nezilovite, rinmanite, gahnite and braunite. Piemontite-(Pb) forms purplish-red imperfect crystals up to 0.5 mm x 2 mm in size and occurs also in random aggregates. D_(calc) is 4.282 g/cm~3. It is biaxial (-), á= 1.835(10), ?= 1.885(10), ?= 1.895(10), 2 V (meas.) = 30-40°, 2V (calc.) = 47°. The IR spectrum is given.