Crystal description
Most often in brilliant, commonly well-formed, triangularly pitted octahedrons. The cube faces are never smooth; though the crystal is unmistakably dicelike, its faces are always uneven but still lustrous. Smooth and shiny hexoctahedrons are usually almost spherical, marked by curved faces. Also in translucent balls with a radiating structure, known as "ball bort" or ballas, and in irregular hard black compact masses known as carbonado. Flat triangular crystals are usually spinel-twinned octahedrons known in the diamond trade as "macles."
