Fire was a key method in extracting stone in the old days – more important than we usually think of. Photo by Per Storemyr

It started with Egyptologist and engineer Reginald Engelbach almost a hundred years ago. By the early 1920s he found evidence that fire would have been used in extraction of the famous Unfinished Obelisk at the Aswan granite quarries. But he was probably wrong when he implied that fire was used to remove poor quality bedrock only. New evidence suggests that fire was used in several steps of extracting obelisks and other stone objects in Ancient Egypt. And written documentation of firesetting may, in fact, go as far back as to the Middle Kingdom, some 4000 years ago. With geologist Tom Heldal as the driving force behind the work, we recently published a brief account of firesetting, based on our findings in Egyptian quarries over the last decade. Read on for abstract of our paper, get a PDF-link and view a gallery of images.

Here’s the abstract:

“The knowledge that heat has an influence on rock properties and can be applied intentionally for changing such properties has existed longer than modern man. Archaeological research has uncovered numerous examples of the use of firesetting in ancient stone quarrying and metal mining. Also in Egyptian quarries, evidence of the use of fire is found. The present paper presents features found in five Egyptian quarries and discusses these on a background of rock properties and possible quarrying technologies. Conclusively, it suggests that the use of fire in stone quarrying reached a highly sophisticated level during the New Kingdom period.”

Full reference and PDF:

Heldal, T. & Storemyr, P. (2014): Fire on the Rocks: Heat as an Agent in Ancient Egyptian Hard Stone Quarrying. In: G. Lollino et al. (eds.), Engineering Geology for Society and Territory – Volume 5, 291-295, Springer International Publishing Switzerland,
DOI: 10.1007/978-3-319-09048-1_56 (preview and PDF).

Previous blog posts about firesetting in ancient stone quarrying:

• Ten quarries of Ancient Egypt: 10 – Firework!
• Burning rock! Experiments with fire setting at the Stone Age Melsvik chert quarries in Northern Norway

A small gallery of images related to firesetting of rocks to extract stone:

Shattered stone surfaces at Chephren’s quarry, Old Kingdom. Firesetting used to peel the block making it suitable for further work with hammerstones to create a sculpture. Photo: Per Storemyr

Adel Kelany of the MSA (Ministry of State for Antiquities) has always been part in our work in Egypt. Here by one of the likely fireset and poundered trenches at the Unfinished Obelisk quarry, Aswan. Photo by Per Storemyr

Firesetting experiment at Aswan. Photo: Adel Kelany

Loads of charcoal in the debris of the Unfinished Obelisk quarry at Aswan. Photo by Tom Heldal

Fire shattered rock surfaces at the silicified sandstone quarries by Gharb Aswan (West Aswan). Most likely a sign of an important stone extraction method in the New Kingdom. Photo: Per Storemyr

Old cracks in the granite at the Unfinished Obelisk quarry at Aswan. Such cracks were very probably induced by fire in the New Kingdom to ease the extraction of granite. Photo: Per Storemyr

Several places are mentioned in our paper, but here’s the location of the most important one, the ancient Aswan granite quarries: