My periodic table poster is now available! Rough octahedra under oil. I'm not sure what process resulted in these shapes: They look sort of crystal-like in overall shape, but the surface looks more mechanically-formed than crystalline. As an alkali earth, barium is reactive enough that it must be kept under oil to prevent rapid deterioration into barium oxide. I chose this sample to represent its element in my Photographic Periodic Table Poster. The sample photograph includes text exactly as it appears in the poster, which you are encouraged to buy a copy of. Source: David Franco Contributor: Ed Pegg Jr Acquired: 16 August, 2002 Text Updated: 4 May, 2007 Price: $23 Size: 0.3" Purity: 99.5%