Copper Smelting Could Have Been Discovered in Connection with the Massive Production of Lime Plaster in the Near East During the Pre-Pottery Neolithic B, which is Much Earlier than Previously Believed.

A common theory is that copper smelting first appeared in the Near East in close connection with the early pottery industry. However, copper smelting may well have been discovered many times in history and at many places. Our hypothesis is that copper smelting could have been discovered when the copper-bearing mineral malachite, accidentally or intentionally, was present in lime-burning kilns. To test our hypotheses, a series of test burnings during which malachite, limestone and solid carbon fuel were present in the same furnace have been carried out. The weight and copper content before and after burning was measured. The weight loss was the result of the evaporation of carbon-dioxide in the limestone and the evaporation of carbon-dioxide as well as water in the malachite. The weight loss and final copper content give a clear picture of the effectiveness of the burning procedure. The mechanism behind the successful smelting was most probably the reaction between the carbon in the solid fuel and the carbon-dioxide released from malachite and limestone when they were heated up. This reaction created the carbon oxide necessary for the reduction of "copper-oxides" to copper. The best conditions for discovering this conversion are likely to have existed in areas with an extensive production of lime plaster in combination with an abundance of native copper as well as malachite. The Anatolian mountains was one of the areas where these conditions were at hand. Massive lime production first began in this region in the PPNB around 10,800 BP. We, therefore, propose that copper smelting could have been discovered at this time in Anatolia. [ABSTRACT FROM AUTHOR]