Used in textile dyeing as a mordant to fix dyes on fabrics, especially wool, helping improve color fastness and enhance dye uptake. Also applied in leather tanning to stabilize collagen fibers and improve heat resistance of leather. Employed in water treatment as a coagulant to aid in the precipitation of impurities. Used in laboratory settings for crystallization demonstrations due to its deep violet crystals and as an example of a coordination complex in chemical education. Historically utilized in photography for toning and in lithography processes. Occasionally used in educational experiments to grow crystals for science projects.