81 Heigh-Ho, Silver! 1545 LONG BEFORE California's gold rush, the discovery of silver in the Andes mountains in 1545 sparked an explosion of wealth for Spain. Entrepreneurs flooded Potosi, then part of Peru, drafting Indians to unearth the precious ore. (To numb themselves against hunger and fatigue, they chewed on as many as 95,000 baskets of coca leaves in one year alone.) Between 1550 and 1650, Potosi's mines provided up to 60 percent of the world's silver, opening up trade between Latin America, Europe and Asia, particularly China, where silver was worth twice its value elsewhere. By 1640 silver's value in China had bottomed out--hastening the demise of the Ming dynasty and the decline of the Spanish empire. Potosíí's mountain is now mined primarily for tin.