Ancient organo-mineral geopolymer in South-American Monuments: Organic matter in andesite stone. SEM and petrographic evidence

A recent study has shown the presence of artificial construction materials in pre-Columbian monuments at Pumapunku-Tiwanaku, Bolivia. In addition to ancient geopolymer sandstone-concrete megalithic slabs, the Pumapunku site contains puzzling H structures made of andesitic volcanic stone. The SEM study of this gray andesite shows the presence of organic matter: carbon, nitrogen, and minerals: Na, Mg, Al, Si, P, S, Cl, K, Ca. Organic matter is very unusual, if not impossible in a solid volcanic stone and suggests ceramic-like man-made stone. Our research demonstrates that these architectural components manufactured 1400 years ago (ca. CE 600) were fashioned with a type of organo-mineral precursor.