A SMALL-SCALE CINNABAR-MERCURY RETORT: IMPLICATIONS FOR PRE-CONTACT GOLD PRODUCTION

In the ancient world, cinnabar was an important industrial mineral that was: 1) mined, ground, and used as a red pigment (vermilion), and 2) more importantly, in the ancient Andes, cinnabar was also retorted as a source of mercury for use in pre-contact small-scale alluvial gold mining. Use of cinnabar as a pigment dates to 8000 years ago at the Neolithic site of Catalhöyük, Turkey and an ancient retort near Konya, Turkey indicates that mercury was retorted from cinnabar approximately 8000 years ago. Mercury was used by the Greeks and Romans in the amalgamation of gold and this process was described by Pliny the Elder (77 AD).

In South America, cinnabar-mercury occurrences are known in Bolivia, Chile, Colombia, Ecuador, and Peru. Larco Hoyle (1945; 2001), Cabrera la Rosa (1954), Posnansky (1957), Petersen (1970), and Ravines (1978) all connected the availability of cinnabar-mercury occurrences, amalgamation of alluvial gold, and Peru’s massive pre-contact gold production.

Therefore, given the geological evidence for the regional availability of cinnabar-mercury occurrences in Peru and the widespread use of mercury for gold amalgamation in the past- through-to-the-present, it remains only to show how cinnabar could be retorted to obtain mercury. Therefore, a retort was modeled from the racks of double-ceramic retorts shown in Agricola’s De Re Metallica (1556/1912, Book IX, p. 427) and a pre-contact double-ceramic mercury retort from Sierra Gorda, Queretaro, Mexico (Langenscheidt, 1986) where retorting mercury, also known as azogue, dates to the 10^th century BC (Consejo de Recursos Minerales, 1992). Just as mercury is widely used today for alluvial gold mining, this rudimentary process would have produced only mercury, not vermilion, that would have had but one use in the past–small-scale alluvial gold mining.