GSA Annual Meeting in Indianapolis, Indiana, USA - 2018

Paper No. 21-14
Presentation Time: 9:00 AM-5:30 PM


BROOKS, William E., Geologist, Reston, VA 20191

The use of cinnabar (HgS) as a source of mercury for small-scale gold mining in the ancient Andes was first proposed by Cabrera la Rosa (1954): “It is likely that ancient Peruvians knew about the use of mercury for (gold) amalgamation and they retorted mercury from cinnabar ores near Buldibuyo.” The amount of gold produced in pre-contact Peru is hard evidence that is consistent with his assertion, and even today, Peru produces ~1.5 t of gold per month from small-scale alluvial gold mines that use the same rudimentary technique of mercury amalgamation of mm-sized alluvial gold. Retorting and use of mercury in ancient Peru may be inferred from health warnings regarding its toxic fumes and effects on human health as well as the number of Quechua words, ex. llimpi, for mercury. Cinnabar, plant-derived achiote, and insect-derived cochineal were used as red pigments for paint, funeral ceremonies, and make-up; however, only powdered cinnabar was used to decorate gold masks. Therefore, a compilation of cinnabar-mercury occurrences in the Andes is important in assessing the regional availability of this mineral resource for ancient industrial use as pigment, and more importantly, for Pre-contact gold amalgamation and Colonial silver amalgamation.

Ancient mercury retorts are known at Huancavelica, Peru (Rivero and Tschudi, 1851), the largest cinnabar-mercury occurrence in the Andes, and Huancavelica was an important source of mercury for Colonial silver processing. Other important regional occurrences include Aranzazu (Nueva Esperanza) and El Cinabrio, Colombia and Azogues, Ecuador. More than 20 occurrences, including Buldibuyo, are known in Peru: Amazonas (1); Ancash (3); Ayacucho (3); Cajamarca (1); Huanuco (3); Junin (3); La Libertad (1); Lima (2); Pasco (1); and Puno (2) (Petersen, 1970/2010). And, aside from Huancavelica, Giles (undated) indicates several cinnabar occurrences (6), adits, and retorts.