Alexander von Humboldt (1769-1859) travelled to Mexico in 1803/4 and brought back a number of archaeological archaeologica and documents of Mexican illuminated manuscripts. One object from the Humboldt collection is the perfectly preserved ear peg made of obsidian, a volcanic glass. The thin-walled, translucent piece of jewellery piece of jewellery must not only have struck A. v. Humboldt as a technical Humboldt not only as a technical masterpiece, but also because of its material. also because of the material. Because of its hardness and hardness and the sharpness of its edges, obsidian was the most important most important raw material for tools and spear or arrowheads. Only high dignitaries were allowed to wear an ear peg of this size and technical perfection. (M. Gaida 2003)