Contrary to the well-known hypothesis of construction of the Great Pyramids at Giza by carving and hoisting quarried limestone blocks, in 1974 a French research chemist, Joseph Davidovits, proposed a radically different hypothesis that the pyramid blocks are not quarried stone but cast-in-place “concrete” prepared with the soft, marly kaolinitic limestone of Giza that was readily disintegrated in water and mixed with locally available lime and natron. The lime-natron combination, according to Davidovits, dissociates the kaolinitic clay from the limestone and forms an alkali-aluminosilicate (zeolitic) “glue”, which he termed “geopolymer”. The “man-made” hypothesis was proposed as an alternative explanation to the apparent mysteries associated with the “carve-and-hoist” hypothesis in regard to the methods of construction and observations of some “unusual” minerals in pyramid samples that are rare in natural limestone.

The purposes of the present study are to investigate: (a) evidence of microchemical signatures of the proposed lime-natron-clay-based geopolymeric chemistry in the binder phases of the pyramid samples; (b) textural, mineralogical, microstructural, and binder-microchemical comparisons among pyramid samples, natural limestone from Tura, and geopolymeric limestone; and (c) the reported “unusual” constituents in the pyramid samples, if any, and their possible sources.