On September 6, 1622, the heavily laden treasure galleon of King Philip IV’s Tierra Firme Fleet sank in a raging hurricane near the Florida Keys. Two hundred and sixty people and tons of silver, gold, and other precious cargo were lost to the sea. All attempts to locate the wreckage of the Atocha failed until the location of the vast silver cargo and part of the lower hull structure was found July 20, 1985, by Treasure Salvors, Inc.
Over one thousand silver bars were listed on the ship’s manifest. The majority of the ingots were the property of individuals, although four tons of the cargo was revenue; and one hundred thirty-three bars were shipped in thirty-four boxes marked with the red crown mark of Philip IV.
Figure 1. Atocha Silver Bar Symbols
Many of the silver bars were mined and processed in Upper Peru (modern Bolivia). Each ingot was poured into a mold and the struck with the serial number (A), which would be listed on the ship’s manifest. The assayer would then remove his “bite” (B) to attest to the purity of silver. Once purity was established the ingot was struck with the “Ley” or fineness number (C), 2400 being the purest. Each bar other than the royal “Quinto” was subject to 20% tax and was struck with the tax seal (D), often in several locations on the bar, indicating that the tax has been paid. Monograms and designs (E) indicated the owner or shipper. Various other marks (F) of unknown origin were made by various handlers and shippers recording their transaction with the bar. Some bars are dated with the year (G).
Figure 2. Map of Atocha Shipwreck Location