The Minting Process

The illustration below shows the assayer and his Indian slave assistants engaged in producing coins of the mint. The Indian in the center is taking freshly poured strips of silver and beating the strips flat. He then hands the beaten strips to the worker at the left, who cuts the strips into coin planchets. The Indian at the right takes these coin planchets. and puts them one at a time on top of the bottom coin die. He then takes another die and places it on top of the coin planchet and strikes the dies with a hammer, which impresses the die design on both sides of the coin planchet. The newly struck coins are passed to the assayer who weighs them and clips off any excess silver. The coins are now ready for distribution to pay for trade goods, wages and the ever-increasing national debt of Spain.

Due to the method used to make the coins, no two coins look alike. The coins of this period are often called cob coins. This term comes from a simplification of the Spanish phrase, "cabo de barra", or made from an end of a bar. The coins, like the silver ingots that were being mined, are made from a very fine quality of silver. The purity ranges from about 92% to 98% silver with the impurities being copper or platinum depending on which mine the silver came from.