Relationship of Mineralogical Composition to Thermal Expansion, Spectral Reflectance, and Physico-Mechanical Aspects of Commercial Ornamental Granitic Rocks

Abstract

The aim of the present study is to link the thermal expansion, spectral reflectance, and physico-mechanical aspects of different types of commercial granitic rocks with their mineralogical and chemical composition. The granitic rock types were characterized using several analyses, including petrography, chemical, mineralogical, and thermo-gravimetrical analysis using XRF, XRD, and TG/DTG/DSC techniques. The rock types were subjected to several performance tests, such as tests of their thermal expansion, spectral reflectance, and physico-mechanical properties. The results revealed that quartz, albite, and potash feldspar with minor amounts of mica (biotite/muscovite/annite) are the main mineralogical constitutes, in addition to some alteration minerals, such as kaolinite, saussorite, and prehnite. The studied granitic rocks were classified as monzogranite/syenogranite of high K-calc-alkaline and peraluminous characters and are related to late- to post-collisional settings. The thermogravimetrical analysis revealed that the overall mass loss over the whole temperature range up to 978 °C did not exceed 3% of the initial weight for all studied rocks. The results of thermal expansion revealed that the maximum change in linear thermal expansion for all rock types did not exceed 0.015% of their initial lengths at an unusual air temperature of 50 °C. The spectral analysis revealed that iron and hydroxyl ions are the main spectral absorption features that appeared in the VIS-NIR and SWIR regions, in addition to the appearance of the common and distinctive absorption peaks of the main mineral composition. Furthermore, the spectral reflectance demonstrated that the granitic rock types of low iron oxide content achieved a high reflectivity percent in the VIS-NIR and SWIR spectral regions compared with those of high iron content. As a general trend, the granitic rock types of high iron content and/or lower quartz content exhibited a high performance regarding their physical and mechanical properties, such as water absorption, apparent porosity, bulk density, compressive strength, and abrasion resistance. The results of water absorption, density, strength, and abrasion resistance of the studied granitic rocks are in the range of 0.14–0.31%, 2582–2644 kg/m3, 77.85–222.75 MPa, and 26.27–55.91 Ha, respectively, conforming to the requirements of ornamental stones according to the ASTM standard.

Radiological Hazards and Natural Radionuclide Distribution in Granitic Rocks of Homrit Waggat Area, Central Eastern Desert, Egypt

“…The former (older) include calc-alkaline tonalite-granodiorite association (gray) of syn-orogenic rocks with I-type signature. In contrast, the younger assemblages (610-550 Ma) include pink, calc-alkaline to alkaline with late-(I-type) to post-orogenic (A-type) associations [8,9].…”

“…Accordingly, several studies reveal different petrogenesis of Egyptian granitic rocks, varying from syn-late-orogenic to post-orogenic as well as anorogenic granites. Among different granitic rocks, the post-orogenic and anorogenic granites have conspicuous rare metals enrichment that are commonly modified by later hydrothermal processes such as albitization, silicification, and fluoritization [9][10][11][12][13]. This rare metal mineralization includes Zr, Ta, Nb, and W as well as others, such as high contents of rare earth element (REE), U, and Th mineralization, attracting the attention of many geologists and authors to shed light on theses rocks, due to their importance in industrial applications [14].…”

Distribution of Radionuclides and Radiological Health Assessment in Seih-Sidri Area, Southwestern Sinai

“…Crystalline rocks of Egypt, which are dominantly distributed in the Eastern Desert and South Sinai as well as the Uwainate area, constitute the northern sector of the Arabian Nubian Shield (ANS) [ 18 , 19 , 20 ]. These rocks include infrastructure gneisses, ophiolite and arc assemblages, and variable compositions of granitic intrusion [ 21 , 22 , 23 , 24 ]. ANS represents the main crustal juvenile that developed during the late Proterozoic Era by closing the Mozambique Ocean [ 19 , 21 ], exposed from Egypt to Ethiopia on the Nubian side and from Saudi Arabia to Yemen on Arabian Side [ 25 ].…”

Special Issue: Advancement of Functionalized Mineral Materials and Rock

“…The physical and mechanical behaviour, fracture, damage, and evolution processes of geomaterials under various environmental and mechanical conditions, such as thermal, mechanical, chemical, and electrical environments [6][7][8][9][10][11][12][13][14][15][16][17]20,21].…”

“…This Special Issue covers numerous aspects of functional mineral research. These topics focus on various themes, including the analysis of mineralogical composition and its effects on the physico-mechanical properties of geomaterials, the investigation of the impact of triaxial stress on the damage creep behaviour of geomaterials, and the evaluation of the thermophysical and mechanical characteristics of rocks under high-temperature circumstances [6][7][8][9][10][11][12][13][14]. The research conducted on these topics also involves various experimental and numerical techniques, such as digital image processing, Discrete Element Method (DEM), and analytical solution and simulation [13,[15][16][17][18].…”