Zinc for discovering pure metallic zinc, even though Swedish chemist Anton von Swab had distilled zinc from calamine four years previously. In his 1746 experiment, Marggraf heated a mixture of calamine and charcoal in a closed vessel without copper to obtain a metal. This procedure became commercially practical by 1752. William Champion's brother, John, patented a process in 1758 for calcining zinc sulfide into an oxide usable in the retort process. Prior to this, only calamine could be used to produce zinc. In 1798, Johann Christian Ruberg improved on the smelting process by building the first horizontal retort smelter. Jean-Jacques Daniel
Schlangenberg Nature Reserve the surface where erosion removed large amounts. About 200 million years ago aqueous metal solutions filled the cavernous rocks. Primary ores were created mostly consisting of Sphalerite, Marcasite and Galena. The process continued and the ore close to the surface decomposed due to the influence of carbon dioxide and water. In this process as a secondary ore calamine ZnCO which is known as calamine developed. Presumably the Celts had been the first digging for the calamine in the region. Ancient Celtic and Roman coins dated between 100 BC and 92/93 AD as well as remains of a Roman settlement proved