Mexican authorities said Friday they have found a tiny amount of radioactive material that had been stolen along with the pickup truck that was carrying it, AP reported. The head of the national civil defense office, Luis Felipe Puente, wrote in his Twitter account that the pen point-sized piece of iridium had been found just north of Mexico City. He said it was under guard and being taken to a safe location. The iridium, used in an industrial inspection device, was enclosed in a casing about the size of a pen. Puente said it was still in the casing when found. The pickup truck carrying the iridium was stolen earlier this week and was later found at a different site.