Impurities? Did they send the wrong isotope by any chance?I bought 10 g of iridium metal powder from China for my neutron activation experiments. It was comparatively cheap (still expensive, but a good deal compared to e.g. gold: $170 for 10 g of the world's rarest metal, and I'll get to sell it back on ebay). But when it came, it made my Geiger counter go off pretty furiously without any activation at all. Looks like some there's some uranium or thorium contamination. And I couldn't even clean it up with aqua regia, although the fact that it didn't dissolve in aqua regia confirms that it is indeed iridium.
Despite the amazing cross-sections of both of its isotopes, it looks like I'll just have to sell it on ebay - I can't use it with this high of a background count, because my neutron source is very weak and statistical tests have to be done to make sure anything happened at all. Stupid cheapish Chinese iridium and its radioactive impurities.
(also, I don't know how strong it is, but have you checked in case it might have been strong enough to irradiate something/somebody on the way?)
On both hemispheres!May is usually all seasons at once. One day you're shovelling snow from your driveway, next day you're barbecuing.