Ancylite-(Ce) from quartz-calcite-chlorite veins in phyllite of the Opava Mountains (SW Poland)

Abstract

Ancylite-(Ce) oc curs in quartz-cal cite-chlorite veins cross cut ting the fo li a tion of phyllite in the Dewon Quarry in the foot hills of the Opava Moun tains of the east ern Sudetes, south-west Po land. Ir reg u larly shaped grains of ancylite are up to 67 mm long and 22 mm wide. The compositional range of ancylite, de ter mined by elec tron microprobe, is ex pressed by the em pir i cal for - mula: (Sr0.65–0.55Ca0.19–0.14Fe0.03–0.00)S0.87–0.69 Ce0.58–0.50Nd0.26–0.22La0.26–0.21Pr0.06–0.05Sm0.05–0.04Gd0.07–0.03Dy0.01–0.00)S1.29–1.05 (CO3)2 (OH1.07–0.99F0.22-0.0.06)S1.29–1.05 × 0.95–0.93H2O. Ancylite crys tal lized di rectly from CO2-rich hy dro ther mal so lu tions as the last min eral in the veins fol low ing pre cip i ta tion of cal cite. The so lu tion tem per a ture, es ti mated us ing var i ous chlorite geothermometres, was in the range of 260–340°C.