My periodic table poster is now available! Concave Lump. This lump has some interesting patterns of its oxide on the surface. It looks like it was formed by melting in a cup-shaped crucible. Source: George (not 007) Lazenby Contributor: George (not 007) Lazenby Acquired: 20 November, 2002 Price: Donated Size: 0.75" Purity: 99.99%