The Spanish dollar or peso (literally, "weight") is a silver coin which was minted in Spain after a Spanish currency reform in 1497.

Thanks to the vast silver deposits that were found in Mexico (for example, at Taxco, Guerrero, and Zacatecas, Zacatecas), and to silver looted from Spain's possessions throughout the Americas, mints in Mexico and Peru also began to strike the coin. Millions of pesos were minted over the course of several centuries. They were among the most widely circulating coins of the colonial period in the Americas, and were still in use in North America and in South-East Asia in the 19th century. They had a value of one dollar when circulating in the United States. During the US Civil War the US Government first issued paper money backed by Spanish dollars.

The coin is roughly equivalent to the silver thaler issued in Bohemia and elsewhere since 1517. The German name "thaler" was adopted in English as "dollar", referring to all such coins.

The peso nominally weighed 550.209 Spanish grains, which is 423.900 troy/avoirdupois grains (0.883125 troy ounce or 27.468 grams), .93055 fine: so contained 0.821791 troy ounce (25.560 grams) fine silver. Its weight and purity varied significantly between mints and over the centuries.

The peso had a nominal value of 8 reales ("royals"). The coins were often physically cut into eight "bits", or sometimes four quarters, to make smaller change. This is the origin of the colloquial name "pieces of eight" for the coin, and of "quarter" and "two bits" for twenty five cents in the United States.

Long tied to the lore of piracy, "pieces of eight" were manufactured in the Americas and transported in bulk back to Spain (to pay for wars and various other things), making them a very tempting target for seagoing pirates. Some pirates were among the richest people in the world. In fiction, such as Robert Louis Stevenson's Treasure Island, pirates' parrots are commonly represented as being trained to cry out, "Pieces of eight!"

External Links, Resources, References

• The Spanish dollar and the colonial shilling