Lead tetroxide (minium) - Pb3O4
Lead tetroxide is a mixed oxidation state lead(II), lead(IV) oxide, and it contains lead(II) and lead(IV) in the ratio 2 : 1. In the past this compound was used a lot as a protective paint for reducing the rusting rate of iron objects. The common name for this kind of paint was minium, and this same name sometimes is used for the pure compound as well.
The sample, shown here, is appr. 250 grams of solid. This solid is remarkably compact. The solid, shown here also is of very high purity (better than 99.6% by mass). The pure material has a very vivid color.