90 pound Silver Ingot- Recovered from the Nuestra Senora De Atocha.
On September 6th, 1622, the treasure galleon of King Phillip IV’s Tierra Firme Fleet sank near the Florida Keys during a severe Hurricane. Two hundred sixty people perished and tons of silver, gold and other precious cargo were lost to the sea. This shipwreck lay undiscovered for more than 300 years, when it was finally found on July 20th, 1985 by Melvin Fishers’ company, Treasure Salvors, inc. 35cm long, 13.5 cm wide, 9.1 cm thick. 90lbs. 11.84 oz.
The silver from these bars was mined at the Porco Mine, Quijarro Province, Potosi Dept., Bolivia. Porco is located in territory that immediately prior to the Inka conquest was controlled by the Qaraqara señorío, a loosely organized array of ethnic groups that occupied a large part of what is now south-central Bolivia. The Qaraqara, in turn, constituted half of the larger Charkas confederation. Historical research suggests that during this period Porco was the location of silver mines as well as an important ritual center that attracted pilgrims from throughout the southern Andes. Unusually large pieces of ore, the mines, and the mountains in which they were located all had important spiritual significance to indigenous groups.
The Inka conquest of the region appears to have been motivated primarily by the rich mineral resources that occur there. While the Qaraqara presence at Porco has not yet been verified in the archaeological record, survey and excavation have yielded abundant evidence for Inka exploitation of the zone, which, according to Spanish chroniclers, produced much of the silver used to decorate the Temple of the Sun in Cuzco. The archaeological remains indicate that the Inka developed a centralized infrastructure comprised of multiple facilities with different purposes – housing, storage, administration, mining, and mineral processing – that were dispersed within an approximately 1 km area in which the mines are located. No evidence for the manufacture of finished products has been recovered thus far.
The Inka sites at Porco are characterized by modest architecture, and the low density and diversity of artifacts recovered during excavations suggests that they were used only to support mining and smelting operations, most likely on a seasonal basis. Workers probably included mit’a workers (laborers drafted on a rotating basis from conquered groups) and yanakuna (specialists attached to elite households), but not mitmaqkuna (permanent colonists).
Spanish control of the mines began with the arrival of Gonzalo and Hernando Pizarro in 1538, whose holdings in Porco were among their most lucrative enterprises. Both the historical and archaeological records indicate that the exploitation of silver deposits was decentralized and small-scale. Every site constructed by the Inka was re-occupied by people engaged in metal processing, and the technology used for smelting and refining ores was extremely varied. However, production prior to the 1570s appears to have been largely in the hands of indigenous miners who leased veins from Spanish owners. These individuals relied heavily on native technology, such as “huayrachinas”, or wind furnaces, for smelting silver ore.
While large quantities of silver were extracted throughout the sixteenth century, Porco’s productivity was eclipsed by the spectacular output from Potosí after its discovery in 1545. The mines of Porco, however, continued to be worked on a large scale by both mita and wage laborers into the following century. However, after the introduction of mercury amalgamation for refining ores in the 1570s, control over production passed to Europeans who could raise the capital for the construction of large mills.
During the 1700s exploitation was only sporadic, and by the end of the century the state had halted the assignment of laborers to that zone. A resurgence of mining occurred at Porco in the late nineteenth century when the demand for industrial minerals, especially tin, led to the establishment of a modern concentration plant by Porco Tin Mines, Ltd. Since then tin extraction, and more recently, zinc, has been pursued on a large scale. The mines at Porco are now operated by COMSUR, a large international company, although a number of local mining cooperatives also work the deposits. Most workers reside in the nearby village of Porco, or the settlement of Agua Castilla, which is located adjacent to the railway.