Study Chips Into Pyramid Stone Theory

A study chips away at the theory that Egypt's pyramids were built of solid stone, with French and U.S. scientists saying concrete was used for some blocks.

The research promotes the theory that ancient Egyptian craftsmen had the skills and materials to cast the pyramids' huge blocks. Egyptologists reject the claim, insisting that the 2-ton stones were carved then dragged up the pyramids for placement, the Times of London said.

But a study of the Giza pyramids found two types of stone -- one from quarries and one man-made.

"There's no way around it. The chemistry is well and truly different," Gilles Hug of the French National Aerospace Research Agency said. The study by Hug and Michel Barsoum of Philadelphia's Drexel University will appear in the Journal of the American Ceramic Society.

The researchers used X-rays, a plasma torch and electron microscopes to compare small fragments from pyramids with stone from the Toura and Maadi quarries. They said they found "traces of a rapid chemical reaction which did not allow natural crystallization."

Hug and Barsoum said they believe the concrete method was used only for the stones on the higher levels.