2006 Philadelphia Annual Meeting (2225 October 2006)
Paper No. 90-1
Presentation Time: 1:30 PM-1:45 PM


BROOKS, William E.1, PIMINCHUMO, Victor2, SUAREZ, Hector2, JACKSON, John C.3, and MCGEEHIN, John P.3, (1) Geology, George Mason University, MS 5F2, Fairfax, VA 22030, webgeology@aim.com, (2) Instituto Nacional de Cultura, Trujillo, Peru, (3) U.S. Geol Survey, 954 National Center, Reston, VA 20192

Ancient Andeans exploited mineral occurrences for pigments as well as copper, gold, silver, platinum, and mercury for artisanal metalwork. Five samples of mineral pigments from a recently excavated mural at Tacainamo, the Chimu capital of Chan Chan, northern Peru, were analyzed by X-ray diffraction. Results indicate that the Tacainamo muralists used: 1) atacamite [Cu2Cl(OH3)], a copper halide mineral to produce green pigment; 2) azurite [Cu3(CO3)2(OH)2], a copper carbonate for blue; 3) calcite [CaCO3], a common calcium carbonate mineral for white; 4) cinnabar [HgS], a mercury sulfide for red; and 5) goethite [HFeO2], an iron oxide for yellow-brown. Binder for the pigments is unknown. A C14 date on woven plant material from the site gave a 2 sigma date of 1412-1614 AD. Sourcing the Tacainamo pigments is difficult due to the large number of mineral occurrences in the region, lack of a geochemical database for comparison, and destruction of the original surface outcrop from mining. For example, Huancavelica, the most well-known cinnabar occurrence in Peru, has been mined since the 1500s, and is one of 5 cinnabar localities listed by Petersen (1970). There are probably many other cinnabar occurrences associated with hot springs or the abundant epithermal mineral deposits in the cordillera that may have been exploited. Similarly, there are at least 20 atacamite localities and goethite is a ubiquitous alteration product associated with epithermal systems throughout the Andes.

2006 Philadelphia Annual Meeting (2225 October 2006)
General Information for this Meeting
Session No. 90
Archaeological Geology
Pennsylvania Convention Center: 109 AB
1:30 PM-5:30 PM, Monday, 23 October 2006

Geological Society of America Abstracts with Programs, Vol. 38, No. 7, p. 233

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