Editing Crucible (section)

===Chalcolithic===
Crucibles used for [[copper]] [[smelting]] were generally wide shallow vessels made from clay that lacks [[refractory]] properties which is similar to the types of clay used in other ceramics of the time.<ref>Rehren T. & Thornton C. P, 2009, ''A truly refractory crucible from fourth millennium Tepe Hissar, Northeast Iran'', Journal of Archaeological Science, Vol. 36, pp2700–2712</ref> During the [[Chalcolithic period]], crucibles were heated from the top by using [[Blowpipe (tool)|blowpipes]].<ref name="hauptmann">Hauptmann A., 2003, ''Developments in copper Metallurgy During the Fourth and Third Millennia B.C. at Feinan'', Jordan, P. Craddock & J. Lang, Eds, Mining and Metal Production Through the Ages, British Museum Press, London, pp93–100</ref> Ceramic crucibles from this time had slight modifications to their designs such as handles, knobs or pouring spouts<ref>Bayley & Rehren 2007: p 47</ref> allowing them to be more easily handled and poured. Early examples of this practice can be seen in Feinan, Jordan.<ref name="hauptmann" /> These crucibles have added handles to allow for better manipulation, however, due to the poor preservation of the crucibles there is no evidence of a pouring spout. The main purpose of the crucible during this period was to keep the ore in the area where the heat was concentrated to separate it from impurities before shaping.<ref name="rehren03">Rehren Th., 2003, ''Crucibles as Reaction Vessels in Ancient Metallurgy'', Ed in P. Craddock & J. Lang, Mining and Metal Production Through the Ages, British Museum Press, London pp207–215</ref>

A crucible furnace dating to 2300–1900 BC for [[bronze casting]] has been found at a [[religious precinct]] of [[Kerma]].<ref>{{cite journal |last1=Childs|first1=T|last2=Killick|first2=D.|title=Indigenous African metallurgy: nature and culture |year=1993 |journal=Annual Review of Anthropology |volume=22 |pages=317–337|doi=10.1146/annurev.an.22.100193.001533|jstor=2155851}}</ref>