A Comparative Review of Mechanical and Petrographic Properties and Their Role in Estimating the Brittleness Index of Norite: Implications for Geomechanical Applications

Abstract

Norite is a coarse-grained mafic igneous rock dominated by essential calcic plagioclase and orthopyroxene. Norite is known for its toughness, and it has a high compressive strength which makes it important in engineering. This paper examines the mechanical and petrographic properties of norite, including their relevance to geomechanical applications. Despite improvements in brittleness estimation, standardizing brittleness indices remains a challenge due to geological variability, incompatible petrographic techniques, and difficulties in relating mineral composition to mechanical behavior. Current brittleness models mainly rely on mechanical properties, often ignoring key petrographic factors like grain size, mineral composition, alteration, and porosity. This limits their accuracy, especially for complex rocks like norite. Few studies integrate both petrographic and mechanical data, creating a gap in fully understanding the geomechanical behavior of norite. This review was carried out by examining the origin, formation, and petrographic properties of norite, and a comparative analysis of its strength, flexibility, mineral structure, and fracture mechanics was conducted, highlighting their importance in the engineering and mining industries. The results of this study highlight how factors like strength, brittleness, and durability influence norite’s suitability for geomechanical applications in mining, tunneling, and construction. Furthermore, the results outline that the mineral composition of norite affects its strength, with quartz enhancing strength and altered minerals like feldspar, mica, and biotite weakening the rock and making it more prone to fracturing. These results are important for tunneling projects as they help predict how rocks will behave, ensuring tunnel stability and better design in underground support systems.

Keywords

• norite
• brittleness index
• mechanical properties
• petrographic properties
• rock strength