ПОХОДЖЕННЯ УНІКАЛЬНОГО ФІОЛЕТОВОГО ЦИРКОНУ З АФГАНІСТАНУ

Unique unusually large dark violet zircon crystal from Afganistan was studied by EMPA, LA-ICP-MS, XRD and FTIR methods. Obtained results reveal its well preserved crystallinity, absence of definite zoning, low concentration of isomorphic impurities, weak “flat” Eu-minimum and Proterozoic age ~1875 Ma. IR spectra show two narrow peaks of structural OH groups at 3405 and 3274 cm^-1 and absence of structural molecular water. All these features are non-typical for magmatic silicate rocks or from Oligocene carbonatites. The Proterozoic marbles are considered the most likely source of this zircon.