Found this on Wiki: A sample of radioactive material was seized by German police in May 1994. This consisted of a complex mixture of elements, including about 10% by weight plutonium, with the remainder consisting of 61% mercury, 11% antimony, 6% oxygen, 2% iodine and 1.6% gallium. A formula reported for the powder component of the mixture was Hg6Sb2O8 (mercury(II) cyclopyrorthoantimonate), with some of the mercury present in its pure metallic form.