Promoting research, discussion, and debate about technologies used in Ancient Egypt

Know your stones


Dolerite BallsWhen looking at ancient Egyptian carvings, many people do not realise the differences between the types of stones and how very important that difference is. Huge monuments like Karnak, Luxor Temple, Hatshepsut’s Temple and even the tombs in the Valley of the Kings are carved in relatively soft sedimentary stone (typically limestones and sandstones) and are relatively easy to cut and carve with bronze tools. However, there are also magnificent examples of masonry and statuary carved in very hard igneous stones like granite and basalt that are impossible to carve using bronze tools. However the majority of egyptology books do not point out this difference and sometimes completely misunderstand the significance of this scientific fact. Why is this important? Arguably because it demonstrates that we have a huge gap in our understanding and it shows that the Ancient Egyptians possessed a technology that egyptologists have not yet discovered.

As a scientist when I look at a magnificently carved hieroglyph on the Thutmosis I obelisk at Karnak, I marvel at how the hieroglyph was created, not what it means. For example, the hieroglyph that forms the sound kheper in the coronation name of Thutmosis I (akheperkare) is a finely carved scarab beetle.

If you look at the exquisite beauty of the workmanship of this one hieroglyph and consider that there is no way this can be replicated today using hammers, steel chisels, and sand polishing then how did the Ancient Egyptians achieve this 3,500 years ago and why has this important question not been asked before? I would argue this is because most writers on egyptology are primarly historically trained and do not appear to have the scientific understanding to question the processes and technologies involved.

To aid this understanding, here is a table of relative hardesses I have compiled of typical minerals and materials. The table was first created in 1812 by the German geologist and mineralogist Friedrich Mohs.

Mohs HardnessMineral
1.0Talcum, Graphite
2.5Mica, Chalk
3.0Calcite, Limestone, Marble, Sandstones
3.5Copper, Bronze
4.0Dolomite, Flourite
4.5Apatite (Tooth enamel)
5.0Cast Iron
5.5Window Glass
6.0Feldspar (Part of granite)
6.5Tool steels (files & chisels)
7.0Quartz, Diorite, Dolerite, Basalt, Flint
8.0Topaz, Garnet
8.5Emerald (Tungsten carbide - synthetic)
9.0Corrundum (Sapphire & Ruby)
9.5Silicon Carbide (Synthetic)

As you can see copper and bronze are typically around 3.5 on this scale and will not even scratch glass. Therefore the idea that copper tools would cut granite is fatuous. Surprisingly, even steel tools cannot do the job either. Today tungsten carbide or diamond tipped tools are used in either pneumatic hammers or high-speed rotating drills to cut granite with precision. However do not be confused with ‘breaking up’ granite which can be done with a steel chisel, but this is largely uncontrollable compared with the extremely fine cutting that you can see in the obelisk carving above.

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