" Not-withstanding the fact that cutting granite with copper chisels is an impossibility, Egyptologists have asserted that the pyramid builders predated the Bronze Age, and, therefore, were limited in their choice of metals with which to make their tools. Therefore, they say that copper was the only metal that the ancient Egyptians used to fashion the stones with which they built the Great Pyramid. They say this while evidence of prehistoric iron—proving that the ancient Egyptians had developed and used it when building the Great Pyramid—is in the keeping of the British Museum. The discoverers of this piece of iron go to great lengths to argue for and document its authenticity, as John and Morton Edgar point out in their book Great Pyramid Passages.
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Despite the [...] testimonials, because the chronology for the development of metals did not include wrought iron in the age of the pyramids, the specialists at the British Museum concluded that this wrought-iron artifact could not be genuine and must have been introduced in modern times.
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The profession as a whole has been unable to cope with the idea of a piece of wrought iron being contemporary with the Great Pyramid. Such a notion goes completely against the grain of every preconception that Egyptologists internalize throughout their careers concerning the ways in which civilizations evolve and develop.
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Egyptologists have a vested interest in continuing their teachings as they have taught them for the past century. To do otherwise would be to admit that they have been wrong. The iron plate is just a small, though significant, item in a large collection of anomalies that have been ignored or misinterpreted by many academics because they contradict their orthodox beliefs. "

― Christopher Dunn , The Giza Power Plant: Technologies of Ancient Egypt