Calcite and Willemite

Unlike birds or insects, humans cannot see ultraviolet (UV) light. Its wavelength is too short for our optic cells. Many natural substances, such as this mineral, absorb UV light and release the energy it contains back into the environment in the form of long-wave light. To the human eye, they begin to glow colourfully in the dark. This object was part of the UV display case in the permanent exhibition of the Museum Natur und Mensch from the early 1970s until 2008.