A year and a half later, after extensive scanning electron microscope (SEM) observations and other testing, Barsoum and his research group finally began to draw some conclusions about the pyramids. They found that the tiniest structures within the inner and outer casing stones were indeed consistent with a reconstituted limestone. The cement binding the limestone aggregate was either silicon dioxide (the building block of quartz) or a calcium and magnesium-rich silicate mineral.
The stones also had a high water content—unusual for the normally dry, natural limestone found on the Giza plateau—and the cementing phases, in both the inner and outer casing stones, were amorphous, in other words, their atoms were not arranged in a regular and periodic array. Sedimentary rocks such as limestone are seldom, if ever, amorphous.
Editor's Note: This research was supported by the National Science Foundation (NSF ), the federal agency charged with funding basic research and education across all fields of science and engineering.
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