The Egyptian Pyramids
EXTRACTION AND ELABORATION OF THE STONES
There are various theories which explain how the blocks of stones were extracted and cut. The methods were distinct depending on the hardness of the stones. The ancient Egyptians classified the stones according to the appearance, strength and location. They differentiated between limestone, sandstone, alabaster and granite, but basalt and other stones were grouped under the same terms.
The limestone rocky masses were located in scaled horizontal layers. The ancient Egyptians exploited only the layers of high quality. They extracted the materials selectively choosing the ones most resistant to the weather; for this they had to use several times wells and galleries. They only worked in the open sky in those places where the layer of stone to be exploited was too high or was directly below the covered rock.
Both in the case of the limestone as well as sandstone, first the blocks were cut from the square or rectangular base according to the use it was going to be put to. The exploitation of the quarries was done advancing from above to below, cutting the blocks by means of making fissures and separating them from the base. Wooden hammers and metal tools were used, in the beginning copper, and later, bronze. In a later period ( 10TH to 8TH century A. C.), metal chisels and wedges were used. One can find prints of the use of these utensils on the walls of the quarries: in the oldest ones one can see small marks, and in those exploited in later times, these reached up to 50 cm length and are extraordinarily parallel, which makes one think of the use of large metal chisels. But the pyramids of Gizeh were built almost two thousand years before, so that the method of extraction was not so "sophisticated”.
It seems the theory considered valid till recently that the dismounting of the blocks was done by means of the use of wedges which, on becoming wet, would expand and separate the blocks, is not certain for none of the different types of stones. The procedure consisted of inserting chisels which later would stick to the wedges to increase the pressure and thus separate the blocks. In the case of granite, to find the best pieces it was necessary to go much deeper. There is a theory which sustains that a method used to arrive at the lowest layers was to make a huge fire over the rocky mass. With the heat the granite would break easily. The fire would extinguish when it reached a layer where the material was of the best quality.
For the elaboration of hard stones, basically granite, tools of dolerite were basically used, a stone of strong resistance to blows. The hardness of the stone impeded the use of metal chisels. The procedure was the following: the adequate block was selected and the upper pieces were slowly removed by means of blows with dolerite stones until the desired form was achieved. Afterwards, to remodel the surface and engrave inscriptions, metal chisels were used. The polish was done with powdered quartz mixed with sharpened stone.
The ancient Egyptian quarries could be considered a kind of workshop of sculpture, since in them worked, apart from labourers, quarry masters, sculptors and chroniclers. The pieces were practically terminated in the quarry itself, from where they were brought out with the inscriptions completed. The transport of these Pharaonic works was done by means of ramps formed of pieces of stone covered with a layer of sand and mud from the Nile. The pieces were mounted over wooden sledges that were pushed by bullocks or by men, as can be found in some papyrus and reliefs..