Black quartz, also called smoky quartz, is made when traces of aluminum in the silica crystal are irradiated. This prevents the atoms from absorbing light. These crystals vary from a smoky gray to abyssal black with intricate geometric patterns. Each sold separately, the crystal you receive may not be one depicted in the images. Length: 2.25 in - 3.5 inWidth: 1 in - 2 inHeight: .6 in - 1.5 inWeight: 1.8 oz - 3.9 oz