## 2 Geological and Petrographic Overview of Norite
### Petrographic Properties of Norite  
The attributes of the major accumulated minerals in norite are characterized by their texture, mineral composition, and variations in mineral proportions [26]. Grain size, packing density, mineral contact types, and mineral composition (primarily plagioclase and orthopyroxene) are the main petrographic factors affecting the characteristics of norrite [27]. These variations (grain size, packing density, mineral contact types, and mineral composition) influence the brittleness and strength of the rock as well as the reaction of the rock to stress. In general, a coarse grain size, high feldspar content, and well-developed mineral contacts enhance the mechanical stability of the rock [27; 28]. These properties are key factors in determining the ability of a rock to withstand stress-induced damage.  
The minerals in norite possess varying mechanical properties, such as strength and stiffness, which contribute to the overall heterogeneity of the rock [27]. The strength and weathering resistance of norite are influenced by its feldspar content, as [PERSON] et al. [28] (2019) detailed that plagioclase feldspar, pyroxene, and anorthite are minerals that make up 60-80% of norite rock. [PERSON] et al. [27] (2022) also added that 20-30% of norite is made of orthopyroxene, which is usually enstatite or hypersthene, influencing the mechanical strength and brittleness of the rock.  
Norite visually displays a coarse-grained texture with large, visible mineral crystals, which result from slow crystallization that occurred deep within the earth's crust. Norite contains an insignificant amount of olivine and has accessory minerals such as magnetite and ilmenite, which contribute to its density and texture [28]. The strength of the rock is influenced by its grain size, wherein coarser grains often have higher mechanical strength [7].  
Norite exhibits a porphyritic texture, with larger crystals of plagioclase or orthopyroxene set within a finer-grained matrix (Figure 3). This arrangement can affect how the rock reacts to external stress, resulting in higher mechanical strength [27]. [PERSON] et al. [28] (2019) examined the packing density of the rock and discovered that the solidity of norite is enhanced by the stacked packing of plagioclase and orthopyroxene grains, which improves its strength. Furthermore, [PERSON] et al. [27] (2022) conducted a study on the grain area ratio and emphasized that the grain area ratio (GAR) measures the proportion of individual mineral grain areas to the total rock area (see Equation (1)), with a higher GAR indicating better mineral interlocking and greater rock durability.  
The GAR (grain area ratio) represents the proportion of the total area occupied by grains relative to the overall area analyzed in a selected thin-section image. It quantifies the grain content as a percentage of the reference area observed under the microscope. The GAR specifically refers to an area ratio, not a volume ratio [27].  
A thin-section examination is used to analyze the petrographic aspects of norite by observing its mineral composition, texture, and optical qualities under a polarizing microscope. The geometric characteristics of mineral grains can be determined through visual examination, microscope examination, and automated analytical element mapping techniques [29]. [PERSON] [30] (1974) depicted that norite composed mainly of plagioclase, hypersthene, olivine, hornblende, augite, and cummingtonite has a medium-grained texture with a hypidiomorphic-poikilitic structure through thin-section analysis.