Gold: History of Use, Mining, Prospecting, Assay & Production
Oct 23, 2011· It is estimated that there are over 20,000 ancient stone ruins scattered throughout the mountains of southern Africa. An aerial view of the Great Zimbabwe -- click to enlarge. The most impressive of these is The Great Zimbabwe. This sprawling structure is thought to have been built in the 11th century AD. The walls extend 250 metres (820 feet ...