Quantitative Minerological Analysis of Some Granite Rocks of Deoghar Jharkhand

Crystalline minerals in granite rocks has been quantatively analysed by powder X-ray diffraction (XRD) and Scanning Electron Microscope supported with Energy Dispersed Spectroscopy (SEM-EDS). SEM microphotograph reveals that rock is dominated by brightly illuminated quartz imbedded in the matrix with mica and other minor minerals. The X-ray mineral composition data have been plotted with SEM-EDS mineral composition, data shows that the composition obtained by two technique are in consistent within the experimental limit and in good agreement. Further plot of chemical composition of constituent oxides of granite sample by XRD and SEM-EDS confirm the consistency of two technique and similarity with Jharkhand mean granite composition. Silica composition have been plotted with trace element Pb, Ba, Zr, Rb, and Alumina composition with Pb , Ba, Zr and Rb shows that these elements are randomly imbedded in the matrix with almost uniform composition. Al2O 3 composition have been plotted with Ba, Pb, and Zr shows almost constant composition in all the five samples. Based on XRD and SEM-EDS results, it was reveals that granite sample from the study areas are peraluminius rocks composed of mainly quartz, muscovite, kaolinite, chlorite and albite.


Introduction
Abraham Werner gave the first definition of granite "Granite is an aggreagate rock which consist of Quatz , Fieldspar and Mica united each other in granular texture ( Middlemost 1986). Jharkhand is one of the leading mineral producing states. It is one of the leading producers of coal, kyanite, gold, silver, bauxite, feldspar, uranium, quartz and colour granite. Jharkhand have high grade metamorphic rocks which have undergone metamorphism under amphibolite to granulite facies (Fisher 1984). Granite rocks (Indian Mineral Year Book 2015) are produced from many quarries located throughout the Jharkhand for mixing and matching stone.Granites are coarse-grained rocks with a mottled appearance. They comprise a mixture of glassy white, pink or red alkali feldspar, minor amounts of dark minerals, and often white, sodic plagioclase (Amral 2006). Their low density and resistance to weathering means that they usually form high, rugged terrains. Faryada and co-worker (1995,2015,2020) have studied minerals and their textures in high pressure or ultra-high pressure (U) HP) metamorphic rocks provide quantitative evidence about the thermal regime during subduction, the depths that the rocks reached and their rates of exhumation. However, these rocks commonly display a pervasive amphibolite to high-temperature (HT) granulite facies overprint of the (U)HP mineral assemblages that was evidently imposed during exhumation, yet the mechanism causing the warmer thermal regime remains unclear.
Geologists use it either in a restricted sense, or as a blanket term for granitoids of acid or intermediate composition (Klika 2016). Their complex of varied origins give rise to a great variety of types. Granites are normally classified on the basis of their relative model proportions of quartz, alkali feldspar and plagioclase. Chemical classification (Seven 2009) based on the principle of alumina saturation has been discussed. These are peralkaline, meta-luminous, sub-aluminous and peraluminous. Granitoid rocks in bulk chemical compositions also contain distinctive suites of minor minerals. Granites have a broad range of physical and chemical properties. The suitability of a granite for any purpose is decided by its physical properties which meet the specification established for the purpose. Granites are mostly used because of their pleasing appearance and physical strength. Chemical properties are less important than the physical properties. However, the chemical composition determines many physical properties of granites, particularly its resistance to weathering. D B Clarke, (Clarke 1992) was of the opinion that the chemical composition of a granitoid rock or any igneous rock, reflects sum of the effects of the source and subsequent processes. The composition of the source rock (Chirsty 2016) has the most important influence on the composition of the rock and contain chemical fingerprint of the source material. We determine the mineralogical composition of granite by two different methods. Quantitative characterisation of mineral phases of granite stones are not available in spite of advance analysis instruments and software. Therefore this study with advance analytical instruments will be helpful in deciding the better and efficient applications granite rocks.

Experimental
Five samples (approx. 1-3 kg each) from Deoghar district were collected and analysed for major oxides and trace elements. The average chemical index of alteration (CIA) value of all samples is 48 (Shao andYang 2012, Behzad et.al 2016), which lies within the accepted 30-55 range for unweathered granites. Loss on ignition (LOI) was determined by calcining the samples for 2 hours at 900•C in an electric furnace. Whole rock powders were analysed for major and minor elements using X-Ray diffractometer(Rigaku Japan) and Scanning Electron Microscope supported by Energy Dispersive Spectrophotometer (SEM -EDS) (Jeol, Japan; JSM-6390LV) .The Chemical compositions are analyzed by EDS. The accuracy of the analyses (Carton and Lyman 2004) for the major elements is better than 1% for SiO 2 and 2% for other major elements, 2-5% for minor elements and better than 10% for trace elements. The precision of the data was expressed as the residual standard deviation (RSD), which in general for all the trace elements is much less than 4%.

X-Ray Diffraction (XRD)
In order to determine the mineral content in rock power samples were characterised by X-ray diffractometer (XRD).The corresponding spectrum of samples S1A to S5A are shown in figure 1-5 and analysed results (Zhoua et.al. 2018, Hubbard et.al. 1988,Omotoso et.al 2006 are recorded in table 1.  The plot of intensity counts against 2Θ shows different peaks in 2Θ the presence of quartz, muscovite, chlorite, albite, kaolinite, pyrite, K-fieldspar, biotite, amphibole, illite, calcite, plagioclase and apatite in different proportion in some of the samples. Some of the 2Θ peaks are very weak and hidden. At least six type of constituents minerals were identified in major to miner quantity.. Quartz was dominant 73.60 to 75.50% and muscovite was in between 12.30 -13.50%. In addition to these eight types of minerals iron titanium oxides zircon and rare earth elements also present in small amount as shown in

Scanning Electron Microscope (SEM) Coupled With Energy Dispersive Spectroscopy (EDS) Analysis
The morphology of surface of granite samples S1A -S5A are shown in figure 6-10.The SEM-EDS spectra are shown in figure 11-15 and corresponding oxides are shown in table 2. The slight deviation in value than 100% may be attributed to elemental interference, matrix effect and overlap effect. At least, ten types of constituent minerals were identified in the granite sample. Quartz was a dominant constituent with more than 70% and second is muscovite, K-feldspar and alkali feldspar were contained in higher concentration than plagioclase. In addition to these minerals, iron-titanium oxide, zircon and rare earth elements were also observed in a small amount. The present composition was characteristic of the ordinary granite. Iron-titanium oxide, pyroxene, apatite and pyrite were also observed in a small amount.   It confirmed that silicate is the major mineral phase followed by alumina.

Comparison of Data Measured by XRD and SEM-EDS Two Technique
Oxides compositions in granite by two technique XRD and SEM-EDS for Na, Mg, Al, Si, Ca, Ti, Fe etc. have been plotted in figure 16 -22. The comparison of % XRD data with % composition determined by SEM-EDS of Al2O3, SiO2, Na2O, K2O, FeO, TiO2, and MnO shows that data are comparable within experimental error and also comparable with mean composition value of Jharkhand granite. All the five samples S1A to S5A shows that both the technique results are comparable within experimental error.   (Pawloski and Calif 1986,Xie et.al 2018and Regelink 2014) and recorded in table 3. The heavy metals content in the rocks are consistently lower . Heavy metals have low mobility in relation to Ca ++ and Mg ++ and high persistent in the environment. Ba is associated with K because of similar in ionic ratio. Low content of heavy metals in rocks are consistent with very low metal content of the granitic parent material. The use of SEM -EDS is important to confirm the presence of elemental composition of the minerals. . Among the trace elements the precession and therefore accuracy of Ni, Cr, and Ba is significantly less than for Rb, Sr, Zr, Nb, Cu and Zn, Ba. Ni, Cr, and Ba are regarded as only semiquantative below 30 ppm level, Pb, Sr, Zr, have satisfactory precesion and accuracy down 1to 3 ppm. Figure 23 to 29 shows the plot of trace element with SiO2 and Al2O3 compositon. Figure 23 shows that Pb concentration is increasing with SiO2 concentartion. On the other hand all other element shows almost constant composition with respect SiO2 and Al2O3 composition. Figure 27,28 and 29 shows the variation Ba, Pb and Zr with Al2O3 which shows uniform distribution of these metal in all the five samples.

Results and Discussion
Five rocks samples S1A-S5A were subjected for XRD and SEM-EDS analysis . The XRD spectrum are shown in figure 1-5 and data are recorded in table 1. The SEM micro-photographs are shown in figure 6-10 , EDS spectra are shown in figure 11-16 and data are tabulated in table 2. It is clear that the photograph that bright portion is composed by quartz. It is clear from the table 1 and 2 that rock are composed of mainly 10 minerals out of which silica have the highest composition 70-75% followed by alumina 12-14%. The plot of X-Ray composition against SEM-EDS composition for various minerals shows that these two technique have good agreement within the experimental limits. The variation of heavy metals with respect to silica composition are shown in figure 23 -26 shows that variation of heavy metals are almost uniform in the granite matrix. Figure 26-28 shows the variation of heavy metals with respect to Al 2 O 3 composition which is also uniform. The trace metals data obtained by X-Ray are recorded in table 3. Figure 30-31 shows that XRD and SEM-EDS plots are in good agreement. On the basis of XRD and SEM-EDS data, rock was classified as Peraluminius rock.
Major element data of five samples are shown in table 1 & 2 indicate that the granite gneiss are high in silica (70-75%) and alumina 12-14% content, Na 2 O (3-4%) and K 2 O (2-3%). The rocks are characterized by total iron content as On the basis of geochemical compositions and petrographic characteristics five samples of granites were collected. Major and trace element data for all granites are listed in table 3. Granite is a medium-to coarse-grained igneous rock with essential quartz and muscovite. Granites (Cross 1903& Maitre 2002  Peraluminous rocks (Willner 1990) are igneous rocks that have a molar proportion of aluminium oxide greater than that of sodium oxide, potassium oxide and calcium oxide combined as compared with peralkaline, metaluminous, and subaluminous. Peraluminous minerals include biotite, muscovite, cordierite, andalusite and garnet. Peraluminous rocks are igneous rocks that have a molecular proportion of aluminium oxide higher than the combination of sodium oxide, potassium oxide and calcium oxide (Blatt 1995). This contrasts with peralkaline in which the alkalis are higher, metaluminous where aluminium oxide concentration is lower than the combination, but above the alkalis, and subaluminous in which aluminia concentration is lower than the combination.
Peraluminous corresponds to the aluminum saturation index values greater than 1 (Ludington 2008) Peralumneous magmas can form S-type granitoids and have been linked to collisional orogenies and to the formation of tin, tungsten and silver deposits. (Mlynarczyk 2005

Conclusion
Deoghar Jharkhand granite were analysed by two different X-ray and SEM-EDS technique. Remarkable good agreement were found between XRD quantitative analysis and SEM -EDS analysis. Mineral composition of samples investigated by XRD analysis reveal that rocks, granite silica SiO2 (70-75%), Al2O3 (12-14 %) as shown in table 1 and SEM -EDS analysis shown in table 2. It is confirmed that Si is highest composition followed By alumina in the granite rock sample S1A-S5A. Further, rocks have been classified as peraluminus which can form S-type granitoids. The rocks also contain valuable minerals in trace amount in ppm range. The composition of silica and Alumina have been plotted for Na2O, K2O, FeO, TiO2 and MnO determined by two different technique have good agreement, and close to standard mean value of Jharkhand. Further silica and alumina dependence on trace element shows that Pb is increasing with silica on other hand other element shows the constant composition with silica and alumina..