Silica Content (SiO2): Granite has a high silica content, typically ranging from 65% to 75%. This high silica content is largely due to the abundance of quartz, a major constituent of granite.
Alumina (Al2O3): Alumina, usually in the form of aluminum oxide, constitutes about 10-15% of granite's composition. It's primarily sourced from feldspar minerals in the granite.
Alkali Metals: Granite contains significant amounts of alkali metals, particularly potassium (K2O) and sodium (Na2O), which generally range between 3-8%. These elements are derived from alkali feldspar minerals like orthoclase and microcline.
Calcium Oxide (CaO): Though less abundant than silica and alumina, calcium oxide is still a notable component of granite, usually around 1-2%. It mainly comes from the plagioclase feldspar.
Minor Components: Granite may contain trace amounts of other oxides like iron oxide (FeO, Fe2O3), magnesium oxide (MgO), titanium dioxide (TiO2), phosphorus pentoxide (P2O5), and manganese oxide (MnO). These contribute to the minor variations in color and physical properties of different granite types.
Acid Resistance: Due to its high silica content and the lack of easily carbonated minerals, granite is quite resistant to weathering by acids. This makes it a durable material in environments exposed to acid rain or acidic pollutants.
Radioactive Elements: Granite often contains trace amounts of radioactive elements like uranium, thorium, and potassium-40. The concentration of these elements can vary, but they are typically low and not harmful in most applications.