Grossular, calcium aluminum silicate, is a member of the garnet family of minerals. It is common in many localities, and often forms extremely sharp and beautiful crystals with forms that display the symmetry of the isometric (cubic) crystal system. The most characteristic is the rhombic dodecahedron, a shape with twelve identical rhomb-shaped faces. Single, distinct crystals of grossular typically form by recrystallization of impurities within limestones that have been altered (metamorphosed) by heat, pressure and invasive hot mineral solutions from deep underground. A well known locality for excellent grossular crystals is in Mexico, near the town of Morelos.