Boleite is a rare and complex halide mineral composed of lead, silver, copper, and halogens, with the chemical formula KPb₂₆Ag₉Cu₂₄Cl₆₂(OH)₄₈. It belongs to the halide mineral group and crystallizes in the cubic crystal system. Boleite is especially famous for its perfect cube-shaped crystals, which are often well-formed and highly attractive. The mineral is best known for its deep indigo to royal blue color, which is caused by the presence of copper in its structure. It typically appears opaque, although some thin crystal edges may show slight translucency. Boleite has a vitreous to sub-adamantine luster, giving it a bright and reflective surface that enhances its visual appeal.