A nice crystal of radioactive betafite, from he locality that is widely recognized s having produced the best samples of this species.  Although they are found relatively close to the United States in an area where field collecting is still possible, the emphasis on "border security" over the last several years has made these a bit of a headache to bring into the country.  I have heard a couple first hand accounts of collectors detained at the border and searched, because apparently these are radioactive enough to set off the particular sensor at the nearest border crossing... so now people don't try to bring them in anymore.