Used as a flux in analytical chemistry for decomposing minerals and ores, especially in sample preparation for spectroscopic analysis. Helps dissolve refractory oxides and silicates by forming soluble sulfates. Commonly used in gravimetric analysis to separate silica from other components. Also employed in metal surface cleaning and pickling due to its ability to remove oxides. In some industrial processes, it acts as an acidic catalyst or pH adjuster in non-aqueous systems.