Colorized scanning electron microscope micrograph of inner casing limestone.

1. How the Great Pyramids of Giza were built has remained an enduring mystery. In a recent paper‡, that has caused a worldwide stir, it was shown that at least some of the limestone blocks in the Great Pyramid of Khufu were not natural. The evidence is compelling, multifold and includes the presence of: • Amorphous Si-containing areas consistent with a relatively rapid precipitation reaction and incompatible with our understanding of how sedimentary rocks form. • Areas with appreciable amounts of Si in combination with elements, such as Ca and Mg, in ratios that are not known to exist in sedimentary rocks. • Areas between the natural limestone aggregates, with chemistries reminiscent of calcite and dolomite - not known to hydrate in nature - that were hydrated. • Submicron silica-based spheres that strongly suggest that, at one time, the solution was basic. • An outer Ca-phosphate layer, on an inner casing sample - cemented by an amorphous silica phase - that cannot be natural. • The sophistication and endurance of this ancient technology is simply astounding and has major ramifications to history and archeology. • ‡ M. W. Barsoum, A. Ganguly and G. Hug, J. Amer. Ceramic Society, 89, 3788-3796 (2006). Evidence for Reconstituted Limestone in the Great PyramidsMichel Barsoum, Drexel University, DMR 0503711 100 µm Colorized scanning electron microscope micrograph of inner casing limestone. The red areas are the amorphous silica cementing phase that glue the black natural limestone aggregates together.