The mystery of alluvial gold mining in former Peru
Peru has been producing metals for thousands of years and is today the leading gold producer in Latin America; However, to date, the indigenous mining techniques used to produce industrial quantities of gold in Peru prior to the untouching have not been described. Industrial amounts of gold are produced in only two ways: 1) gravity separation/mercury (mercury amalgamation), and 2) cyanide. Therefore, understanding today's gold mining methods is key to understanding gold mining in the past. For example, in 2018, large open-pit gold mines in Peru produced 123767 kg of gold using cyanide, and small-scale alluvial gold mines produced 18,875 kg of gold using heavy separation plus mercury.
Mercury ore, cinnabar, is a sulfide mineral widely used in the ancient world:
1) It is mined, selectively ground and widely used as a blood-red pigment (cinnabar) on ceramics, gold masks, frescoes, statues, funerals
2) It is distilled to produce mercury. In the ancient Turkic language more than 8,000 years ago, there was a record of obtaining mercury by distilling cinnabar; in Roman times (Pliny the Elder, 77 AD); Middle East, Ancient Mexico;
Medieval Europe; California in the 1840s. Mercury has been used for centuries to recover gold by mixing it with mercury.
Currently, the most important use of mercury worldwide is small-scale alluvial gold mining. Other uses include: automotive switches, batteries, chlor-alkali production, dental amalgam, explosives, fluorescent lamps, luminescent toys, medical devices, pharmaceuticals, mirror backings and neon lights. Thus, since cinnabar has been mined and dried in the past, none of the above uses existed in the past, it can be concluded that there was only one use of mercury mined in the past - mercury amalgamation for placer gold.
Alluvial gold is known to be the main source of gold for ancient humans and provided two-thirds of the gold ever produced. In Peru, alluvial gold deposits are widely distributed; However, the most famous regions include northeastern Peru, east-central Peru, and southeastern Peru. These alluvial resources may have provided most of the gold that Atahualpa used as a ransom for his release from Spain before his execution in 1533.
Today's mining techniques provide insight into pre-contact alluvial gold production in ancient Peru. The references and data here are also consistent with the pre-exposure Peru consolidation. Given that the use of cyanide only dates back to the 1880s, the amount of gold produced in Peru before contact suggests that ancient blending was key to gold production in the past. The availability of mercury, represented by a compilation of cinnabar mercury deposits, is important for the study of the mineral resources of the ancient Andes and their uses. Huancavelica remains the most famous mercury mining point, now closely followed by Chonta.
The availability of mercury cinnabar is suitable for studies of mineral resource uses, both as a source of red pigment (cinnabar) and as a source of pre-exposure to Peruvian mercury ore. Among them, the use of mercury for gold mixing in the present and past helps explain the indigenous techniques that produced incredible gold production in ancient Peru before the arrival of Europeans. In addition to ancient cinnabar mining in Huancavelica, there are references and evidence of ancient mine operations in Chonta, Cuipan and Queropalca and pre-Inca gold mining in Pataz.
Some natural mercury is available, such as in Huancavelica or Chonta; However, dry distillation of cinnabar is a simple process that dates back to ancient times in the world. In Peru, distillation uses readily available materials such as cinnabar, clay for ceramic stills, cooling water, and fuels such as charcoal, coal, grass, or wood. Just as today Peru uses mercury in the small alluvial gold mines of Madre de Dios or Marañon, in the past, mercury would be extracted from the cinnabar mines in Peru, distilled, and then used in pre-contact gold production.
