My periodic table poster is now available! Romanechite from Jensan Set. This sample represents manganese in the "The Grand Tour of the Periodic Table" mineral collection from Jensan Scientifics. Visit my page about element collecting for a general description, or see photographs of all the samples from the set in a periodic table layout or with bigger pictures in numerical order. Source: Jensan Scientifics Contributor: Jensan Scientifics Acquired: 17 March, 2003 Price: Donated Size: 1" Composition: (Ba,H2O)2Mn5O10