engleski

Crystal morphology of sanidine phenocrysts from Zvegor, Republic of Macedonia

This paper presents the results of the research carried out on sanidine crystals from Zvegor, Republic of Macedonia. 572 crystals were collected for research: 326 single crystals and 23 randomly intergrown crystals, 100 right-handed and 123 left-handed Carlsbad twins. Results show that left- and right-handed Carlsbad twins are almost equally represented at this locality. Goniometric measurements showed the appearance of six forms: {; ; ; ; 010}; ; ; ; , {; ; ; ; 110}; ; ; ; , {; ; ; ; 130}; ; ; ; , {; ; ; ; 001}; ; ; ; , {; ; ; ; -111}; ; ; ; and {; ; ; ; -201}; ; ; ; . XRPD analysis of the sanidine - crust (Fds_C), showed that it consists of a mixture of three different phases: calcite as a dominant phase, illite and sanidine. The mixture of these phases could be a result of the feldspar crystal alteration which was primary of sanidine composition. The alteration could have been due to influence of solutions which also affected other components of the rock. It could also be a result of a post crystallization reaction of sanidine with the altered rock. XRPD analysis shows that the core of the sample (Fds_S) is sanidine.

Carlsbad twins; randomly intergrown crystals; sanidine; single crystals; Zvegor

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