The German physician and naturalist Philipp Franz von Siebold (1796-1866) stayed in Japan from 1823 to 1829, collecting comprehensive botanical, zoological and mineralogical material. After returning to the Netherlands, he published Fauna Japonica and Flora Japonica, based on his zoological and botanical collections. These books are still standard works for botanical and zoological research on Japan. The third part of the possibly planned three-volume edition, the Mineralogia Japonica, was never published despite the existence of a mineral collection. However, there are clues that a publication was planned. Siebold had put his assistant, Heinrich Burger, in charge of work in mineralogy and related fields. The mineral collection is kept in the Biodiversity Center Naturalis, Leiden, and a variety of Burger's documents on mineralogy are preserved in the Siebold Archive at the Ruhr University Bochum. In Siebold's "De Mineralogica Japonica", the editors try to reconstruct the "Mineralogia" by bringing together the mineral specimens in Leiden with Burger's documents at the Ruhr University Bochum. The Mineralogia Japonica provides us with first-hand knowledge about the geological and mineralogical situation in early nineteenth-century Japan. Those interested in mineralogy and geology and in the history of science in general will find the book a fascinating source of information on natural resources and the development of natural history in Japan and in Europe.