Multivariate Statistical Analysis of Phyllite Samples Based on Chemical (XRF) and Mineralogical Data by XRD

摘要

It is presented the results obtained of a multivariate statistical analysis concerning the chemical and phase composition,\udas a characterization purpose, carried out with 52 rock phyllite samples selected from the provinces of Almería and\udGranada (SE Spain). Chemical analysis was performed by X-ray fluorescence (XRF). Crystalline phase analysis was\udperformed by X-ray powder diffraction (XRD) and the mineralogical composition was then deduced. Quantification of\udweight loss (100° and 1000°C) was carried out by thermal analysis. The aims of this investigation were to analyze and\udcompare the chemical and mineralogical composition of all these samples and to find similarities and differences between\udthem to allow a classification. Several correlations between results of the characterization techniques have been\udalso investigated. All the data have been processed using the multivariate statistical analysis method. The XRF macroelements\ud(10) and microelements (39) data generate one macrogroup with two new subgroups (1 and 2), and an isolated\udsample. In subgroup 1 of macroelements, a positive correlation was found between XRF results and geographic location\udcharacterized by lower MgO content, which is associated to its geological origins. When multivariate statistical analysis\udis applied to results obtained by XRD, two groups appear: the first one with a sample with zero percentage of iron oxide\udand the second one with the rest of the samples, which is classified in two groups. A correlation is observed between the\udalkaline content (XRF) and illite (XRD), CaO and MgO with dolomite and indirectly between the weight loss after\udheating at 1000°C and the contents of phase minerals that lose structural water (illite + chlorite) or carbon dioxide\ud(dolomite). The present investigation has interest and implications for geochemistry and analytical chemistry concerning\udearth rocks and silicate raw materials