My periodic table poster is now available! Etched block. This is an interestingly etched block of high-purity aluminum, showing the crystal zones. I used it as the main feature in an article I wrote for my Popular Science column. Source: Ethan Currens Contributor: Ethan Currens Acquired: 14 October, 2008 Text Updated: 14 October, 2008 Price: Donated Size: 1" Purity: 99.99%