There are white calcite veins diagonally cutting the bedding of a series of gray-black limestone. With careful observation, we can see the milky white semi-transparent rhombohedral calcite crystal, brittle and cleavable, which is the water-free calcium carbonate with chemical composition CaCO₃. It is formed by the intrusion, cooling and crystallization of magnetic thermal fluid along fissure after the sedimentation and diagenesis of limestone.