The Cairo Museum is a treasure house containing many unusual artifacts. Very often, many of these objects are ignored as visitors flock to see, quite understandably and rightly, the more exotic of the displays, particularly those belonging to Tutankhamen - the enigmatic and young Eighteenth Dynasty pharaoh.

Catalogue Number JE6075
But if you have a little extra time for viewing in the Museum, there are two very unusual stone vessels to attract your attention. The first one is in cabinet 13, on the right-hand side of the entrance foyer. This vessel, Cairo Museum catalogue number JE6075, is made of calcite, sometimes known as Egyptian alabaster. This stone has a dark yellowish hue and is banded with different shades of white and yellow. Calcite is a translucent stone. If an electric light, or a candle, is placed inside a calcite vessel in a darkened room, you will be rewarded by the stone's exterior glowing with an exquisite luminosity. Calcite quarried in Egypt is between Mohs 3 and 4 in hardness, and my experimental drilling and sawing tests revealed that flat-ended copper tubes and flat-edged copper saws, using sand as an abrasive, were needed to drill and saw this stone. Serrated saws perform poorly on calcite. Ancient hieroglyphs and reliefs were cut with flint or chert chisels and punches; an examination of the marks made with test flint tools on calcite samples show similarities with hieroglyphs incised into ancient objects. Test cutting with copper and bronze chisels showed an unacceptable loss of metal from their edges.

The cabinet information gives Saqqara as the vessel's provenance and dates it to the First or Second Dynasty. The vessel is circular, about 30cm in diameter, comprising of three, separated circular compartments. Their purpose is unknown, but they could have been intended for containing different liquids or fragmented materials. Two concentric circular ridges, about 2mm wide at the top, 5mm at the bottom, divide the compartments, the outer compartment being about 3.5cm wide, the inner two being about 2.5cm wide. On their inner sides, the ridges curve downward and inward to the compartments' flat bottoms; the outer sides of the ridges are vertical.

Near the bottom of the inner ridge, on its curved inside wall, are four concentric grooves, or striations, about 0.25mm wide and deep. The two slightly deeper bottom grooves travel completely around the vessel's circumference, the upper two part-way around the circumference. It is likely that many concentric striations existed after the initial hollowing procedures, most of them being completely smoothed away.

There is a lip around the vessel's outer circumference, measuring about 4mm in width. The inner, circular dished section, about 10cm in diameter, has a circular hole about 2.5cm in diameter, its depth about 4mm, in the centre. A circular groove, about 2mm in width and 6cm in diameter, surrounds this hole, but is eccentric to it. The inner dished section is undercut.

Discussion of the techniques for making the vessel
Although the vessel's circularity and intricacy suggests the consideration of a lathe, the tools available to craftsmen did not allow this technology to be viable. The test results from cutting calcite with copper chisels demonstrate the unlikely use of a copper tool in use with a lathe. In any case, there is no evidence that lathes existed in Egypt in Early Dynastic times.

The only commonly available materials capable of incising and scraping calcite were flint and chert. However, using brittle flint as a tool material for cutting a rotating piece of calcite is not possible; the tool would immediately break when pressed against rapidly moving calcite. In any event, a lathe would need to be extremely robust, and rotate perfectly without any shake, to enable accurate machining to take place.

Using the experimental evidence as a guide, it is likely that the vessel was roughly shaped into the desired size with flint chisels, punches and scrapers. Stone rubbers and finely ground sand were probably used to finish the surfaces. In accordance with tradition, the main shape would have been completed first, including the whole of the top surface, which was slightly curved before the hollowing of the compartments.

The striations mentioned previously have the appearance of sand crystal damage seen on other ancient artifacts, and my experimentally drilled calcite specimens. It is likely that the craftsman made two tubular drills for the two inner compartments by hollowing the central portions from the ends of two short wooden shafts. The wall of each tube would be slightly smaller than each finished compartment's width, as a drill-tube makes a slightly larger tubular slot than the tube's actual dimensions. Experiments with reed tubes showed their ability to drill calcite with dry sand abrasive, and wooden tubes achieve similar results. A groove was usually made first to prevent the tube 'wandering' around a stone's smoothed surface. Each tube was carefully twisted and reverse twisted until the tubular slot attained the correct depth.

The downward curve on the inner sides of the two ridges is an indication of a tubular drill operated with sand abrasive, caused by the tube's worn exterior diameter at the business end of the drill. I believe the outer compartment was fashioned with flint scrapers and stone rubbers, as was the undercutting of the inner-dished section. A similarly shaped circular stone borer with sand abrasive probably curved this part. A copper tube in use with the same abrasive drilled the 2.5cm-diameter hole. The eccentric groove may be decorative and originally intended to be concentric.

Catalogue Number JE71295
The second vessel, made of schist, is Cairo Museum catalogue number JE71295. The cabinet information indicates that it also came from Saqqara and was probably made in the First Dynasty. The vessel is located in the upper west corridor, opposite room 36. Its purpose was possibly decorative, as it was mounted upon a pole. The hardness of schist is Mohs 4-5.

Commentary and discussion of the techniques for making the vessel
This circular schist vessel was originally carved from a single piece. It was destroyed in antiquity and rebuilt from the surviving pieces. Schist is a stone that can be worked with flint chisels, punches and scrapers, but not with metallic tools. The vessel was painstakingly chiselled, scraped and ground from a solid block with the appropriate flint tools and sandstone rubbers. There are very fine, randomly created striations all over the vessel's surface, clearly the result of rubbing with a fine-grained stone rubber in a multitude of directions. The design of the three petal-shaped pieces makes the onlooker imagine that they have been folded forward from the rim. Not only have these been exquisitely executed by carving, but also the 'spaces' which they are imagined to be folded from must have been drilled and carved to their finished configurations, leaving the rim exposed. This is stone working at its highest level. A copper tube sand drilled the central hole for the pole after the boss had been carved to shape.

I recommend you look at these stone vessels on your next visit to the Cairo Museum. You will be enchanted and mystified by their unique shapes.