 Swedish chemist Georg Brandt ( 1694 – 1768 ) is credited with discovering cobalt circa 1735 , showing it to be a previously unknown element , different from bismuth and other traditional metals . Brandt called it a new " semi @-@ metal . " He showed that compounds of cobalt metal were the source of the blue color in glass , which previously had been attributed to the bismuth found with cobalt . Cobalt became the first metal to be discovered since the pre @-@ historical period , during which all the known metals ( iron , copper , silver , gold , zinc , mercury , tin , lead and bismuth ) had no recorded discoverers . 
