W.B. Emery thought that “no country then or since has achieved such perfection” as that exhibited by the stone vases produced in Egypt during the Predynastic and Early Dynastic periods.¹Emery 1972, 215 An estimated 40,000 such vases were recovered from galleries beneath the Step Pyramid of Djoser (Third Dynasty).²Teeter 2011, 188 Many of them were inscribed with the names of pharaohs of the First and Second Dynasties. Why Djoser chose to accumulate so many vases and place them in his tomb is a mystery. Equally mysterious is how Egyptian craftsmen were able to produce so many stone vases in the first place, especially since many of them were carved from hard stones such as diorite, porphyry, granite, and rock crystal. Surprisingly, the earlier vases tend be carved from the harder stones.

Production

The Egyptians used tubular drills to cut stone. One of these drills is pictured on a Fifth dynasty wall relief.³Located inside the causeway leading to the pyramid of Unas (Fifth Dynasty). The drill has an off-center handle which was used to get it spinning while the weights strapped on either side act as flywheels. The weights also served to apply downward force on the drill bit.⁴Petrie writes: “The amount of pressure, shown by the rapidity with which the drills and saws pierced through the hard stones, is very surprising; probably a load of at least a ton or two was placed on the 4-inch drills cutting in granite. On the granite core, No. 7, the spiral of the cut sinks 1 inch in the circumference of 6 inches, or 1 in 60.” (Petrie, Pyramids and Temples of Giza, Ch. 8) The drill bit itself is thought to have been a copper tube. The cutting action must have been produced by a very hard abrasive which was poured into the circular groove produced by the drill bit. In addition to drills and saws, both W. B. Emery and Sir Flinders Petrie maintained that ancient Egyptian craftsmen also utilized lathes to achieve the perfectly balanced and spherical shape exhibited by the stone vases.⁵Emery 1972, 215 The toolmarks on the inside of the stone vases suggest a continuous and aggressive cutting action. The question naturally arises as to what manner of tools and techniques were employed by the Egyptians to cut hard stones?

Cutting Hard Stone

Many scholars maintain that quartz sand was used as the abrasive, together with tubular copper drill bits. Sir Flinders Petrie considered such theories preposterous. He noted that the cutting action produced by the drill bit was very aggressive. If quartz sand were used it would have left a polished and smooth cutting surface since the cutting action of quartz sand would have been very slow (if it at all!).⁶Petrie, Pyramids and Temples of Giza, Ch. 8 But the saws and drills used by the Egyptian left distinct grooves in the stone that could only have been produced by rapid cutting action.

Petrie suggested instead that the hard stone vessels were cut using saws and drills fitted with gemstone teeth with a Mohs hardness of 9. He even considered the possibility that diamonds were employed by the Egyptians (they have a Mohs hardness of 10) but concluded that the use of diamonds was unlikely due to their rarity. It should be noted that the Mohs scale is not linear. Corundum (Mohs 9) is twice as hard as granite (Mohs 8), while diamond (Mohs 10) is four times as hard as corundum.

Petrie’s theories are generally discounted today. Many textbooks still identify quartzite as the abrasive used by Egyptian craftsmen. But Petrie was no crank. His detailed records and carefully researched reports are models of good scholarship. Petrie thought ancient Egyptian stone cutters used cutting tools with gemstone teeth because the cutting action of their drills and saws was very aggressive. The Egyptians cut granite with apparent ease.

Petrie’s theories were partially vindicated when two researchers at Penn University created a replica of a tubular copper drill bit. They hooked it up to a drill press and tried cutting holes in granite using various types of abrasives and lubricants. Their tests confirm that quartz sand could not have been used to cut hard stones such as basalt or granite.⁷Gorelick and Gwinnett 1983 However, they do not think that hard gemstone teeth were necessary either to achieve an aggressive cutting action but suggest, instead, that emery powder might have been used since it contains significant amounts of corundum with a Mohs hardness of 9. The only known deposit of emery in the ancient world is found on the island of Naxos in the Aegean. It was known to the Roman historian, Pliny (1st century AD), who refers to the super hard abrasive as “naxium” and notes that the abrasive was used to engrave gems.

Further light on the subject was shed by researchers at the Metropolitan Museum in New York who analyzed cutting residue recovered from a hole drilled into a fragment of limestone from Amarna (14th century BC). They found that the powder contained significant amounts of corundum. Thus we have some evidence that the Egyptians used emery for cutting stone. However, the source of the emery remains a mystery since it has a different mineral composition from the emery deposits mined on Naxos.⁸Serotta and Carò 2014, 4 And there is no evidence that the Egyptians imported emery from the Aegean during the Predynastic period.⁹Renfrew 2011, 445 ff. Renfrew notes that there was an explosion in trade during the EB II period and that emery may have been exported from Naxos to other regions in the Aegean in this period. (Renfrew 2011, 451) But not Egypt? Perhaps the Egyptians had another source of emery which we don’t know about. Even so, it must be admitted that the techniques employed by Egyptian craftsmen to produce such precisely symmetrical vases from such hard stones remains a mystery. The cutting lines visible inside the hard stone vases look to me like they were produced with teeth and not an abrasive powder.

Hierakonpolis Stone Vase

One particularly fine example of a hard stone vase comes from the Main Deposit at Hierakonpolis. Although only fragments of the vase remain, enough was found to reconstruct the vase in full. (Note that the pure black material is reconstructed.) The vase was carved from black and white porphyry, an extremely hard stone especially prized by Egyptian vase makers, perhaps due to its resemblance to the night sky.

The symbol of a stork and the sky goddess Bat were embossed on the rim of the vase. The head of Bat is decorated with five stars, each with six points. An identical depiction of the goddess has been found carved into a predynastic stone palette. In later periods Bat would merge with the cow-headed goddess, Hathor.