The discovery of large quantities of gold and silver in the New World following the voyage of Christopher Columbus had a major impact on the subsequent history of the world economy. These two precious metals together with copper were regarded as the standard and measure of value in all societies throughout history. The sudden increase in the supply of gold and silver greatly increased the capacity of individual countries such as Spain and Portugal to finance wars and imports of consumer goods. The new Spanish coin, the real of eight, became an international currency for settling trade balances, and large quantities of these coins were exported to the Middle East, India, Southeast Asia, and China to purchase oriental commodities such as silk piece goods, cotton textiles, industrial raw material such as indigo, and various kinds of spices, later followed by tea, coffee, and porcelain. The trade in New World gold and silver depended on the development of new and adequate mining techniques in Mexico and Peru to extract the ore and refine the metal. South German mining engineers greatly contributed to the transplantation of European technology to the Americas, and the Spanish-American silver mines utilised the new mercury amalgamation method to extract refined silver from the raw ores. Although the techniques used in Mexico and Peru were not particularly advanced by contemporary European standards, the American mine owners remained in business for more than three hundred years, and the supply of American silver came to be the foundation of the newly rising Indian Ocean world economy in the 17th and 18th centuries.