“Japanese and French experts are investigating a new mystery at the 4,000-year-old pyramids — why the pharaohs built geometrical cavities inside the Great Pyramid of Cheops and filled them with mineral-enriched sifted sand.
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“From the outside, the pyramid appears to be built of solid blocks of limestone. But two French architects, Gilles Dormion and Jean Patrice Goidin, discovered cavities which could total 15 to 20 per cent of the structure.
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“The French team used an instrument which measures differences in gravity to find the internal spaces. They then drilled small holes through the 1.0-metre blocks and found sand — but not ordinary sand from the nearby desert.
“Laboratory tests showed it came from another part of Egypt and was sifted and enriched with minerals before being placed inside the pyramid by the ancient architects.”
The dynasty that built the pyramids at Giza had earlier tried to make pyramids almost as tall but had failed with one collapsing and another having to be shortened into a “bent pyramid” shape. Replacing some of the limestone with sand, that I presume it was less dense, would let them save weight and time in construction. Why this particular mixture of sand I cannot guess.
Ah, it was imported sand that was enriched with minerals.
That's no different than the liberal yuppies of today who insist that imported bottled water is far better than the local stuff that comes out of the ground.
Someone probably got rich overcharging the pharaoh for the imported sand.