Original scientific paper

https://doi.org/10.4154/gc.2025.06

Microstructures of feldspar crystals from Pakra Creek valley granite (Papuk Mt., Croatia)

Marija Horvat ; Croatian Geological Survey, Zagreb, Croatia
Viktória Kovács Kis ; HUN-REN Centre for Energy Research, Budapest, Hungary
Jasmina Martinčević Lazar ; Croatian Geological Survey, Zagreb

Abstract

Optical polarizing microscopy, X-ray powder diffraction and transmission electron microscopy with energy-dispersive spectroscopy have been used to study microstructures in feldspars from two structurally and texturally different granite types from Pakra Creek valley (Papuk Mt., Croatia). The porphyritic texture granite contains pink potassium feldspar megacrysts with cross-hatched extinction and tweed pattern, which proved to be intermediate microcline to orthoclase. These crystals have Or > 90% and An=0 composition, and coexist with low albite Or(1.2)Ab(98.8)An(0). The feldspars from the granite with homogenous finegrained microstructure are white in colour and proved to be mixture of lamellar and zoned plagioclase and intermediate microcline. The plagioclase has a Na:Ca ratio close to 3:1 and minor K content (72.2%

Keywords

microstructure; feldspar; granite; Pakra Creek valley; Papuk Mt.; Croatia

Hrčak ID:

328781

URI

https://hrcak.srce.hr/328781

Publication date:

27.2.2025.

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