O seladonicie z Barczy w Górach Świętokrzyskich

Authors

  • Irena Kardymowicz

Abstract

CELADONITE FROM BARCZA IN THE ŚWIĘTY KRZYŻ MOUNTAINSCeladonite occurs as chief component of Lower Devonian (Emsian) tuffite appearing within the sandstones of the Barcza beds. lt forms 70 to 90% of the tuffite mass, occurring in the shape of submicroscopic plates the largest of which attains 0.02 mm. in their direction of elongation. Less frequently has celadonite been reported, in the shape. of spherulites, of 0.08-0.45 mm. diameter (Plate 1, Figs. 3, 4). Pleochroism of individual plates is almost unnoticeable, but aggregated deposits show in the Nγ direction a yellowish-green colour, whereas in the remaining directions they are yellowish or colourless. The investigated celadonite is uniaxial, or discloses an angle of optical axes 2Vα = 5°; it is optically negative. Measured in immersion fluid, the refractive index in direction Nγ is in some prisms = 1.579, in others = 1.581.

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