Few sites in Africa yielded as large a supply of copper ore as the Katanga region of the Democratic Republic of the Congo. While archaeologists believe that even unrefined lumps of copper were used as currency because of their standard size and value, the copper currency that possessed refined casting techniques and artistic value were the ingots shaped as crosses. By 1400 A.D. two distinctive types had developed. One was shaped like an H; the other was formed like an X. The crosses were cast directly on the ground in many sizes. The typical size was about nine and a half inches across, with weights varying up to four pounds. Archaeologists also believe that the larger crosses were made first, followed by the smaller ones as the demands of commerce rose. The crosses were accepted as trade items throughout central Africa. They also served as a source of copper for re-use in jewelry as well as for other currency.