Definitely copper chisels cannot shape granite if we only consider the hardness scale of Mohs - There is an obvious lack of scientific approach when it comes this topic.. I don't know what your standpoint is on this, but if we simply extrapolated the implication this brings to the table of Egyptology we would drastically change our preconceived ideas about their way of being. It seems a lot of the facts that we have are overlooked and their implications forgotten in the void. To carve granite requires somethings of the same hardness or higher which is either diamond or silicon carbide nowadays. Right there the mystery thickens, how in the first place do you get diamond or harder material? This already implies vast mining enterprises.. For me, the profiling of these ancient people is far from being properly understood until those facts are taken into account in our interpretations.