X-rays revealed that Roman cosmetic used tin oxides

A whitish cream in a small canister, which was recently discovered during archaeological surveys of the remains of a Roman temple in London, has been found to contain SnO₂. Archaeologists think the SnO₂ was added intentionally, presumably for use as cosmetic. They believe the unguent was prepared using sophisticated technology: animal fat was heated, possibly with the aim of bleaching it, and the starch was separated by treatment of roots or grains with boiling water, and then white SnO₂ , which is readily produced by heating refined tin metal in air, was added. The non-toxic properties of SnO₂ would also have been desirable, because by the second century AD, the dangers of lead were becoming recognized. XRF and XRD analysis played an important role in the identification of the ancient cosmetic cream. For more information, see the paper, "Archaeology: Formulation of a Roman cosmetic", R. P. Evershed et al., Nature, 432, 35-36 (2004).