There is a closely related item of materials science in the Great Pyramid that you may not be aware of;
The lower part of the original casings stones now missing were coloured red.
[Lehner, M, The Complete Pyramids, 34; Verner, M. The Pyramids, 460]
The red colour was an artificial surface coating of which samples were collected about 1934 by a French explorer, M. Andre Pochan
Pochan, A, The Mysteries of the Great Pyramids, 219-223]
He collected four samples of stone, coated about 0.5 – 2.0 mm thick, three of which were chemically analysed in 1950 at the Sorbonne confirming the paint layer contained iron, manganese and phosphorus in ‘an organic compound’. The Sorbonne report concluded unequivocally. ‘We consider these facts to verify that the Pyramid was indeed painted’
The fourth sample was deposited for safekeeping in the Louvre … where presumably it still is?
.325) The Great pyramid as a Solar Temple - It has been a common feature of 'Solar' temples around the world to be painted red. The use of red paint to denote a religious building is still observed to this day in Tibet (also on the 30th parallel). Pochan (16) says - ' at the tomb of Pen-Meruw at Giza, the name of the Great pyramid is followed by the determinative reserved for solar temples. (This is a pyramid shape, with a small 'pyramidion' on top). 'Khefre' is one of the Egyptian names for the sun (sunrise, daytime, sunset).
The following extract is from Pochan (16), who proved conclusively (?) that the great pyramid, or a part of it, was at some time, painted with red-ochre paint.
He says: 'As I proceeded to measure the casing stones of the great pyramid, a peculiar fact attracted my attention. Some detached blocks lined up a few metres from the pyramid, which apparently had once been a part of the facing, showed a curios red-brown tint on their flat sloping side.
To what phenomenon could this tint - which the blocks' other surfaces did not have - be attributed? To time? Light? To the sand - as unferruginous as it was - that they had covered the blocks for so long? It is hardly likely, for the other surfaces would have shown beginnings of a similar transformation. Moreover, a knife blade penetrates the coloured surface with difficulty and cuts through the other surfaces easily.
Chemical tests gave me an immediate result: the facing blocks were coated with a paint having a ferrous oxide base (red ochre). .Tests carried out on other parts of the sample were negative...', and he continues 'However, it was necessary to verify this fact. The second pyramid still retains part of its casing, which definitely seems to be coloured red fragments taken from the pyramids casing, when subjected to chemical tests, showed the same reaction as those taken from the facing blocks of the great pyramid'. We must also keep in mind that the Sphinx's face is also painted red. Pliny informs us that it was painted because of a cult
However; formal proof that the pyramid was painted came to me in the course of a separate examination of the rather deteriorated casing stones found on the pyramids south face. E. Baraize and I ascertained that some of these blocks showed, on their uppermost horizontal surfaces, traces of red paint corresponding to the breaks between the rocks that had been placed directly above them; the coating was clearly thicker and showed fins'.
As early as the Archaic Period, the panels of the "palace-facades" tombs were painted with bright colours, to represent the mats supposed to close them: the wooden parts were either painted with their graining or simply in red. For the Djoser burial complex, the stone walls were also painted, but under the action of sand loaded winds, the paint has vanished, with the exception of the red ochre on some of the imitated roof beams, and a few traces on the supposed wooden elements. This red colour, for the fluted columns correctly supposed to be of cedar, is odd for those of the entrance, which represent bunches of reed and, accordingly, ought to have been painted green.
It seems that the columns played an important part in the decoration of the "South and North Buildings" frontages (see PM III2, pl. 43). At one third of their height, under the representation of a wooden beam, there ought to have been a painted mat of various colours. It has been possible to restore the "South Building" frontage, with its probable colours as they were during Imhotep's time. The colours used are those which may have been used in the O.K. mastabas of Mehu, Kagemni and Mereruka."
LAUER, Jean-Philippe, Sur l'emploi et le rôle de la couleur aux monuments du complexe du roi Djoser, RdE 44 (1993), 75-80.
Lodestone (or loadstone) is magnetite a naturally magnetised mineral form of mixed iron(2) and iron(3) oxide crystallised in the cubic system. It is the only natural strongly magnetic substance known and the second most important ore of iron after haematite which is a mineral substance is produced by the weathering of magnetite. That is to say, when magnetite is exposed to the atmosphere at the earth’s surface, it turns eventually into haematite a Greek word meaning bloodstone which when roasted and ground makes a red oxide of iron. This is used for many things including jewellers rouge to put a fine polish on metal and some stone, it also to make a paint called red ochre.
There is evidence that Khufu sourced iron oxide in an area west of Elephantine.