unknown

The crystalline structure of many of the heavier, radioactive elements remains unknown. These include astatine, francium, fermium, lawrencium, rutherfordium, dubnium, bohrium, mendelevium, nobelium, seaborgium, hassium, meitnerium, darmstadtium, unununium, ununbium, ununtrium, ununquadium, and ununpentium.