As a precious metal, platinum tends to vary in price with the value of the dollar and the state of the stock market. […] It also depends on the success of the Russian wheat crop. Russia is one of the principal suppliers of platinum (South Africa is the other). When the Russian wheat crop is small, the authorities sell platinum to gain the foreign exchange necessary to buy grain from the United States. This increase in supply brings the price of platinum down. These changes eventually show up in the price of the potassium chloroplatinite. Platinum printers should pray for a strong dollar and a long Russian winter.
ISBN 0871001586, p.167