Global silver trade from the 16th to 18th centuries American mining for the early part of the 16th Century. Mining in the Americas became formally industrialized when the process of mercury amalgamation became popularized. Mercury amalgamation was invented by a Spaniard in central Mexico in the 1550s. Historians dispute what individual was the first to invent the process, however most agree that it was a Spaniard. Mercury was the one of the highest costs of production for the Americas, since much of it had to be shipped. The ratio of Mercury to silver produced was about two to one. Furthermore, German miners introduced the stamp mill and lead smelting
Aztec calendar stone in the next era. The duration of the ages is expressed in years, although they must be observed through the prism of Aztec time. In fact the common thing to figures 676, 364 and 312 is that they are multiples of 52, and 52 years is the duration of 1 Aztec century, and that is why they can express a certain amount of Aztec centuries. Thus, 676 years are 13 Aztec centuries; 364 years are 7, and 312 years are 6 Aztec centuries. Placed among these four squares are three additional dates, 1 Flint ("Tecpatl"), 1 Rain ("Atl"), and 7