The early history of zinc and brass is conditioned by the great volatility of metallic zinc - at temperatures necessary to smelt it, the metal is a gas. About the 1st century B.C. or a little earlier the process of making brass directly from calcined zinc ore and copper in a sealed crucible was discovered probably in Asia Minor. This process was used in the West until the mid 19th century. In India the story is very different and metallic zinc was distilled in retorts from an early date. At Zawar a complex system of mines and intact furnaces still bearing their last charge of retorts have been excavated. The industry flourished from the 12th to the early 19th century A.D. and is almost certainly the direct ancestor of the modern zinc smelting technologies.