Thaumasite in calcic skarns from the Zvezdel-Pcheloyad Pb-Zn deposit, Eastern Rhodopes, Bulgaria.

Thaumasite was found in zoned calcic skarns hosted by the monzonitic rocks of the Zvezdel pluton, Eastern Rhodopes. Associated minerals are wollastonite, clinopyroxene, grossular-andradite garnets, Ti-rich garnets, plagioclase, calcite, quartz, epidote, prehnite, and chlorite. Titanite, apatite and magnetite are present as accessories. The mineral has been characterized using optical microscopy, PXRD, SEM/EDS, EPMA, and FTIR. Thaumasite forms sheaf-like and fan-shaped aggregates, which consist of acicular crystals elongated along the c axis. The IR spectrum of thaumasite is in accordance with the chemical composition and contains absorption bands in the range 3500-3291 cm^-1 (O-H stretching vibrations); 1683, 1650 cm^-1 (bending vibrations of H₂O); 1389 cm^-1 (stretching vibrations of CO₃^2-);1100, 1069 cm^-1 (asymmetric stretching vibrations of SO₄^2-); 882 cm^-1 (symmetric bending vibration of CO₃^2-); 768,742, 680 cm^-1 (Si-O stretching vibrations of Si(OH)₆ octahedra); 670 cm^-1 (bending vibrations of SO₄^2-). [ABSTRACT FROM AUTHOR]