Anthracite is a high-grade variety of coal, renowned for its brilliant black sheen. It forms through the metamorphic transformation of bituminous coal under intense heat and pressure, resulting in a dense, hard rock with a conchoidal fracture and no visible cleavage. The surface is mostly black but can reveal a subtle iridescent rainbow sheen that shimmers depending on light and viewing angle, adding unexpected visual depth to its industrial exterior. Its blocky, angular edges contribute to its rugged appearance, with a submetallic to semi-metallic luster enhancing its reflective qualities.