Gold and Silver Bullion
There were two principal areas of silver mining during Spanish rule over the New World. Mexico and the Viceroyalty of Peru produced millions of ounces per year in silver, as well as a small percentage of gold. Gold was also mined throughout the New World, however, this amounted to only a small fraction of the enormous silver output flowing out of Central and South America.
Bars of precious metal could be almost any size or shape. Large bars of silver produced by the mines will weigh, on average, 70 pounds and will be approximately 90 percent pure. It was typical practice to alloy the silver with copper to increase the hardness of the metal for minting coins. These are known as "official" bars because they are covered by detailed markings that indicate the purity of the bar and stamps that show that the Kings tax was paid. One of the most obvious details on the bar will be a small hole or depression on the bar. This is the spot where the assayer removed a small amount of the metal to be used for establishing the purity of the bar. It is also possible that there are other markings that identify the owner of the bar or possibly where it was produced.
Bars in the shape of wedges were found on the 1715 and 1733 fleets. The wedges were assembled into a pie shape and then packed into a small barrel. The pies were then stacked up to fill the barrel. This arrangement was very convenient for transportation by horses or mules.
Silver bar recovered from a Dutch wreck.
Recent recoveries of silver and gold bars from other wreck sites, most notably the Spanish fleets of 1715, 1733 and the Nuestra Senora de Atocha, indicate that we could also recover gold and silver disks, splashes, finger bars and wedges. The disks are simply ingots cast in a round mold, while a splash was made by pouring molten metal into a hole dug in sand. These types of bars tend to be rare with only a few examples still existing in the world today.
Finger bars are rare and are usually made of gold. Their shapes are typically narrow and long hence the name "finger" bar. Over 200 pounds of gold bars, of this type, were found on the wrecks of the Santa Margarita and Nuestra Senora de Atocha.