Classification of Granitic Rocks Using Stained Rock and µ-XRF Analysis: Comparison with Lithogeochemical Data

Abstract

Classification of granitic rocks are various methods by several researchers in order to limitation of grain size, texture and alteration of the rocks.  The research aims to present the sufficient technique for fine-grained and slightly alteration rock. Modal analysis of three stained rock samples classifies them as alkali feldspar granite, while mineral composition analysis using µ-XRF also classifies them as alkali feldspar granite, with both methods yielding closely comparable mineral percentages. However, classification based on geochemical data differentiates the samples as monzogranite and syenogranite, revealing significant variations in K-feldspar and plagioclase content. This discrepancy is likely influenced by feldspar solid solutions between albite and orthoclase, as well as differences in grain size and alteration. Additionally, µ-XRF element mapping of Al, Ca, Na, K, and Si provides insights into the morphology and crystallography of quartz, plagioclase, and K-feldspar, enhancing the understanding of mineral composition and paragenesis. This study proposes µ-XRF as a valuable method for improving rock classification accuracy under these constraints. While petrography and modal analysis remain fundamental, µ-XRF serves as a complementary technique, particularly for samples with similar limitations. The findings demonstrate that µ-XRF enhances the accuracy and reliability of granitic rock classification, especially for rocks with variable grain sizes.