Imperial Porphyry Quarries near Hurghada, Egypt [Red Sea Mountains]

Theresa Marie Diehl

Abstract

The Imperial quarries at Gebel Dokan, a Red Sea Moutain, are the sole locations in Egypt of an igneous rock called porphyry, coveted by the Romans. Despite the remote location of the quarries, sacrifices were made to obtain the stone and the Romans set up a wide network of support and transport through the Red Sea Mountains. All that is left now are the ruins of the quarry and the remnants of art and architecture made of or adorned with porphyry.

1. Introduction

The Imperial Porphyry Quarries, commonly called Mons Porphyrites, are the only Egyptian source of porphyry, a valued stone quarried largely during the Roman occupation of Egypt. Porphyry itself is not as abundant as granite, limestone, or other building materials, which made it a rare commodity. The remote and harsh conditions under which the porphyry had to be quarried only serves as proof that the stone was considered priceless. This view is substantiated in the fact that Egyptian porphyry was used only in artistic creations of great importance, mainly those commissioned by royalty. The obvious impact of this stone on the culture and art of the Roman Empire and subsequent eras makes a careful study of Mons Porphyrites extremely valuable.

2. Geologic Setting

The Red Sea is undergoing a rifting episode (Meshref, 1990), pictured in Figure 2, where new sea floor is being generated and pushing the adjacent continents apart. The axis of the original rifting event lies slightly to the North and East of where Gebel Dokhan and the rest of the Red Sea Mountains are located, leading to the conclusion that the volcanic rocks of the Mountains are due to the original rifting event. This is confirmed by Hassan and Hashad (1990), who state that the volcanics of the Red Sea Mountains match the compositions of modern ocean island arcs. As well, the area around the modern Red Sea port city closest to Gebel Dokhan, Hurghada, has been seismically active (Figure 3) in modern times due to the rifting. The Egyptian shore of the Red Sea is predominantly made of volcanic rocks and among these are the Dokhan volcanics, Imperial Porphyry composing a small part of these volcanics. Figure 4 shows the distribution of these rocks.

Figure 1: Locations of Precambrian rocks along the Red Sea in Egypt. Gebel Dokhan is identified by the box on the map. Adapted from Gaby, List, and Tehrani (1990).

Hassan and Hashad (1990) give an extensive description of the Dokhan volcanics. These, "almost non-metamorphosed" rocks are mostly porphyritic. The Dokhan volcanics intruded into the sediments that were already there and later granites intruded into the volcanics. There are both intermediate and acidic volcanics in the area. Imperial Porphyry is intermediate. They are named

Figure 2: (left) Map of the current spreading ridges due to rifting in the Red Sea, the original axis or rifting also show. From Meshref (1990). Figure 3: (right) Map of seismicity in the upper Red Sea. Hurghada is labeled with a black box Adapted from Meshref (1990).

for Gebel Dokhan, where they were first identified in the 1930s. In 1967 a geologic survey of Gebel Dokhan was completed and the locations of all the Dokhan volcanics were mapped as shown in Figure 4. In 1979 they were dated to 602 +/- 13 Ma. This age places the origin of the volcanics in the late Proterozoic (Chernicoff, 1999). As seen in Figure 1, rocks of an even earlier age, the Archaean, are also present in the area. This makes the rocks of the Red Sea Mountains among the oldest on Earth.

Porphyry is a general term used to describe igneous rocks that have "phenocrysts in a finer-grained groundmass" (La Maitre, 1989). A phenocryst is a large crystal of a mineral. The cooling history of porphyry is such that the phenocrysts formed when the magma was far below the

Figure 4: Geologic map of Gebel Dokhan. 1. Recent Wadi deposits 2. Gravel Terraces 3. Basic and Intermediate Dikes 4. Red Granite 5. Pink Granite 6. Quartz diorite-granodiorite 7. Dokhan Volcanics 8. Metasediments. From Hassan and Hashad (1990)

surface and the crystals had time to grow large before the magma was suddenly brought to the surface where the rest of the magma cooled quickly, producing crystals too small to be seen (Chalmers, 1941). Imperial Porphyry is a quartz andesite (Hassan and Hashad, 1990), meaning that the white phenocrysts in the rock are actually quartz. Originally, this author thought that the phenocrysts were plagioclase due to their white color but they resisted being scratched by steel and therefore must be quartz since the hardness of plagioclase is less than that of steel. Pictures and photographs of Imperial Porphyry at the quarry and hand samples collected there are in Appendix 1.

3. Roman Quarrying Operations

3.1 Location and Travel to Mons Porphyrites

The settlement and quarry known as Mons Porphyrites lies on Gebel Dokhan. "The quarries are on the Red Sea side [of Gebel Dokhan], high above the wadi called Abu Ma'amel…" (Tregenza, 1955). By examining a map of the Roman roads through the Red Sea Mountains (Figure 5), it is clear that Mons Porphyrites is much closer to the Red Sea than it is to the Nile.

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Figure 5: Map of the Roman roads running through the Red Sea Mountains, major habitations labeled with squares, the Nile in the bottom-left corner of the map, the Red Sea to the far right, and Mons Porphyrites indicated with a box. From Meredith (1952).

It would seem to be logical sense from looking at this map that the porphyry would travel on the road (Via Porphyrites) to Myos Hormos and be transported north on the Red Sea to its final destination. However, there are good reasons, and much evidence, as to why this was not the case. Tregenza (1955) says that the portion of the road close to Myos Hormos is "…Midheis seyl. Midheis seems to mean 'fine, soft sand', and for a long stretch it was loose and yielding underfoot…" Keep in mind that most of these "roads" were really "…unpaved, beaten tracks from which the ancients removed stones and arranged them in a line on each side" (Meredith, 1952). This would be virtually impossible to cross with the wagons used to transport porphyry, which are known to have held up to 210 tons of stone and measured from 7 to 11 ft in wheel span (Meredith, 1952). So, from this information, we know that the destination of the porphyry was actually the other end of the road at Quena (Kainepolis). The direction of the wagon tracks point in that direction (Meredith, 1952) and there are also porphyry ostraka, or cast-away pieces, all along the road to the Nile (Peacock, 1993). Once on the Nile, the stone could be transported all the way to the Mediterranean and to whatever ancient port that demanded the stone.

3.2 Quarry Life

The logistics of living in harsh climates are always intricate, but the Romans managed to keep people alive and working in the porphyry quarries for over two hundred years. The quarries were probably worked lightly from the time of Augustus (31 BC) to Claudius (54 AD), abandoned until Trajan (98 AD), and then worked heavily until abruptly abandoned permanently during the reign of Constantine (337 AD) (Meredith, 1952; Encyc. Roman Emp.). Over these hundreds of years, the emperors built up military installations along all of the roads, some spaced exactly so that travelers would never spend a night without military protection (Maxfield, 1996). As well, the gold mined at Bir Umm Fawakhir (Meyer, 1997) and granite quarried at Mons Claudianus (Peacock, 1997) would have traveled along roads through the Red Sea Mountains, making security extremely important. There was a military installation at Mons Porphyrites, called a castellum (Meredfith, 1952), where a room still exists with pillar wall and door supports still standing (Figure 5). It was built on a terrace in the slope of the mountain (Meredith, 1952), not far above the wadi floor (Figure 6).

Figure 5: Ruins of Pillared Room in Mons Porphyrites Castellum (Credit: Theresa Diehl)

Figure 6: Terrace level castellum at Mons Porphyrites. Mid-ground pillars are also pictured in figure 5. (Credit: Theresa Diehl)

At Mons Porphyrites, there were a few wells from which they obtained their water. Figure 7 shows one that has pillars still standing, "…whether these supported a cistern or merely a roof we cannot say" (Meredith, 1952). From excavations of burial sites, it has been found that the workers ranged in age from teens to about 40 years old but, contrary to what one would think, they do not seem to have died of malnutrition (Maxfield and Peacock, 1998). Apparently the Romans kept their workers well-fed (Maxfield and Peacock, 1998), which indicates a well planned and carried out process of supplying the quarries with what they needed.

Figure 6: Stone supports surrounding a Roman well at Mons Porphyrites (Credit: Theresa Diehl)

There are also a few temples at Mons Porphyrites. Besides two Isis temples, there is a fallen temple to Sarapis at the site we visited (Figure 8). The columns are ionic and there is an inscription that has dated the temple to 117-119 AD (Meredith, 1952). Sarapis is a god that was introduced by the Greeks during their rule in Egypt and is attributed as replacing Osiris all over Egypt and even as the deity of Alexandria; "…hence Sarapis was Osiris, and as such a Savior god, a god of healing, a god of fertility, an oracular god, and a god of the future life" (Bell, 1953). Bell (1953) states that it is possible Sarapis was introduced to bring together the many different cults in Egypt and to unify them with the Greek gods. This would make sense as to why the quarry temple would be to Sarapis, as workers for the quarry would probably have come from a wide variety of religious beliefs. In fact, there is proof from the layout of graves and tombstones that Christians were sent to work Mons Porphyrites quarries (Peacock, 1998; Meredith, 1952).

Figure 8: Fallen Temple of Sarapis at Mons Porphyrites (Credit: Theresa Diehl)

4. Importance of Imperial Porphyry

Obviously, to quarry porphyry was a complicated and expensive task, especially when the quarries operated for two centuries. Why, then, was this stone so important? In fact, it was simply the color of the Imperial porphyry that made it so worth the cost and massive effort of obtaining it. It is well known that purple was the color of the Roman Emperors (Rodley, 1994) and that is why their robes were dyed purple (Chalmers, 1941). In fact, Chalmers (1941) claims that the name "porphyry" actually derives from the shellfish used to make the purple dye; the fluid used for the dye is called "porphyra" and he believed that the literary root "porphyr" was applied later to the purple-colored rock from this source. Today, porphyry does not mean just this specific rock, though all porphyries owe their name to Imperial purple porphyry.

Even after the stone ceased to be quarried, it was important to royalty. The Byzantine Emperors used "…stone salvaged from Rome to veneer the walls of the birth-chamber of the imperial palace in Constantinople… the source of the phrase 'born in purple,' porphyrogenitus…" that was used by the sons of Emperors that were born once "their fathers had come to the throne" (Cockle, 1996). In fact, most of the porphyry works we find today are actually remnants of previous pieces that have been reused throughout history.

Figure 9: (left) Black Porphyry bowl. In Metropolitan Museum (Credit: Theresa Diehl).

Figure 10: (right) Basin support with lions on each end. In Metropolitan Museum (Credit: Theresa Diehl)

Figure 11: Imperial Purple Porphyry bust of Licinius in the Cairo Museum (Credit: Theresa Diehl).

Table 1: Dimensions of porphyry works. Translated and compiled from Delbruck (1932)

Piece	Dimensions
Column	Height (with base) = 2.5m, Diameter = 0.33 m - 0.27 m, Monolith
Column	Height (without pinnacle) = 1.28 m, Diameter = 0.66 m - 0.59 m
Incomplete Column	Incomplete Height = 2.4 m (estimated 3.6 m original), Diameter = 0.44 m - 0.40 m
Incomplete Obelisk	Current Height = 4.13 m, Diameter = 1.2 m - 1.15 m
Basin	Height = 0.36 m, Depth = 0.19 m, Diameter = 1.88 m
Basin	Height = 0.75 m, Diameter = 2.50 m, Inner disk = 0.35 m
Basin	Height = 0.40 m, Diameter = 1.40 m
Basin	Diameter = 2.5 m, Inner disk = 0.35 m
Julianus' Sarcophagus	Length = 3.85 m, Width = 1.83 m, Height = 3.17 m
Helena's Sarcophagus	Length= 2.68 m, Width = 1.84 m, Height = 2.42 m
Constantia's Sarcophagus	Length = 2.33 m, Width = 1.55 m, Height = 2.25 m
Bust of Sarapis	Height = 8.0 cm
Bust of Sarapis	Height = 0.2 m
Bust of Sarapis	Height = 0.15 m
Bust of Licinius	Height of the face = 0.17 m (see Figure 11)

5. Artistic and Architectural Porphyry Creations

5.1 Artistic Uses of Imperial Porphyry

The best possible source of information about sculpture and other artistic work not incorporated into architecture (or reused) is a book published in German by Delbrück (1932). From here, a variety of works, all done with porphyry, are described and photos are provided. Table 1 was constructed from translated information out of Delbrück's book. Everything from royal sarcophagi to basins to columns were carved in porphyry. In the Metropolitan Museum of Art in New York City, there are two examples of porphyry use. One is a porphyry bowl (Figure 9) that was buried in a graveyard near Deir el Bahari (which neighbors the Valley of the Kings) and is the only piece of Egyptian porphyry work that could be found among the references in this paper. There are, however, porphyry statues in the Cairo museum that the Egyptians created so there must have been some quarrying done in pre-Roman times though not to the same extent as the Romans. The bowl was also one of the only pieces mentioned that was made of black porphyry. The other piece in the Metropolitan Museum is a support for a basin. Intricately carved into lions (Figure 10), the porphyry is a deep red, rather than purple, but nonetheless very impressive. The plaque which accompanied the piece said that it was likely "… one of a pair that supported a deep oblong bath or water basin."

In fact, as seen in Delbruck's (1932) work, many of the well-preserved porphyry works are basins. The sizes vary but the largest were 2.5 m across. This means that a huge amount of porphyry must have been quarried and used to make each of them. Even more impressive is an obelisk made of porphyry; a piece that, while broken, still stands over 4 m tall. Delbruck (1932) also lists a number of people who commissioned their sarcophagi to be made of porphyry. Namely, these include Helena (whose sarcophagus is in the Vatican), Julianus, Otto II, Nero, Constantia, and Valentinianus I. Constantine also had a porphyry sarcophagus (Peacock, 1995).

There are a few instances where porphyry has been reworked during the centuries after the fall of the Roman Empire. Most was used in architecture but one instance of non-architectural use was the creation of the Duke of Hamilton's tables (Freyberger, 1993). The panels, each monolithic and over 7 feet long, were well over a thousand years old when they came into the Duke's possession in 1819 (Freyberger, 1993). In fact, Freyberger (1993) says that these are "…probably the largest porphyry works of art outside of Europe…" One of the tables is shown in Figure 12.

Figure 12: One of the Duke of Hamilton's Porphyry Tables. From Freyberger (1993).

5.2 Architectural Uses of Imperial Porphyry

Porphyry also played a part in the building materials used for various architectural works. There are many mentions of porphyry used to make columns. Charlemagne was, in fact, one of the best collectors of porphyry, reusing it in multiple works. In his cathedral, Aachen, there are "…two columns in black porphyry…which can only have come from Mons Porphyrites in Egypt" (Peacock, 1997). Also, porphyry was used in fragments for the floor around Aachen's throne; in a "portable altar from Aldelhausen"; and imported from Ravenna, Italy as a single "exceedingly valuable and very translucent" plaque (Peacock, 1997). No doubt there was much porphyry used in Ravenna, Italy but only two sources could identify the rock as such. It is known that in the 19^th century Bishop Ursus of Ravenna was buried in the cathedral of his name, the Ursiana, "…in front of the altar below a porphyry stone" (Wharton, 1995). Also, there were four red and one black porphyry columns used as part of the 13^th century cathedral in Magdeburg, Germany that are attributed to having been taken from Ravenna (Peacock, 1997). Lastly, Peacock (1995) says that eight porphyry columns were taken from the Temple of the Sun in Rome built by Aurelian and used in the building of St. Sophia in Constantinople. The largest use of porphyry found in the literature was the report of a "gigantic 84-foot [24.8 m] porphyry shaft of Constantine in Constantinople" though the shaft is not monolithic, but hollow (Bailey, 1996).

Most of the porphyry put into great architecture was on a minute scale compared to the buildings themselves. St. Sophia, also called Hagia Sophia and the Great Church, not only had porphyry columns but was also decorated on the inside with rounds of porphyry (Figure 11) (Kahler, 1967). The use of porphyry in small round pieces (rounds) is a common theme throughout the following centuries. In fact, the most famous of marble workers, the Cosmati, scavenged porphyry pieces from Roman ruins and reused them in their church mosaics all across Italy during the XIIth and XIIIth centuries (Hutton, 1950). These families know as the Cosmati, are renowned because

…their work was polychrome and consisted in a geometrical design, a framework, generally of white marble, filled in with great rounds or disks of coloured marble, generally porphyry…taken from the antique ruins of the classical world and sawn up into pieces of various size (Hutton, 1950).

Most of the porphyry that survives today exists within their work. Their craft can be found in at least the following works: mosaics at Peter of Capua's cloister in Rome, friezes at St. Giovanni, mosaics at the Cathedral of Civita Castellana, the altar of Duomo of Ferentina, the high altar of St. Cesareo, a marble screen at St. Lorenzo, the pulpit at St. Maria in Aracoeli, the pulpit at St. Francis at Assisi, the pavement of St. Prassede in Rome, and the tomb of King Henry III in Westminister (Hutton, 1950). It almost seems a shame that the ancient works were cut up by the Cosmati but the beautiful designs they created will probably live on for as long as the original works did.

6. Conclusion

Imperial Porphyry, found near Hurghadda, Egypt, has been an important part of ancient art and architecture. Valued highly for its purple color and white phenocrysts, the stone was quarried at Mons Porphyrites at great cost and for a great length of time by the Romans in Egypt. Despite the troubles that accompanied its acquisition, the Romans built up a wide network of support in the Red Sea Mountains. Today, the works of art that were produced from Imperial Porphyry can be found in numerous countries and will forever be a testament to the stone's long history and truly unique beauty.

7. References

Bailey, D.M. (1996) "Honorific columns, cranes, and the Tuna epitaph." Journal of Roman Archaeology, Supplement Series #19: Archaeological Research in Roman Egypt. D.M. Bailey ed. Thomas-Shore: Ann Arbor, MI. pp. 155-168.

Chalmers, R.O. (1941) “Porphyry, the “Purple Stone: of the Ancients.” The Australian Museum Magazine, 7, 10, 353-354.

Chernicoff, S. (1999) Geology: An Introduction to Physical Geology. Houghton Mifflin Company: Boston. pp. 232.

Cockle, W.E. (1996) "An inscribed architectural fragment from Middle Egypt concerning the Roman imperial quarries." Journal of Roman Archaeology Supplement Series #19: Archaeological Research in Roman Egypt. D.M. Bailey ed. Thomas-Shore: Ann Arbor, MI. pp. 23-28.

Delbruck, R. (1932) Antike Porphyrwerke. W. de Gruyter & Co.: Berlin, 1932.

El Gaby, S, F.K. List, and R. Tehrani. (1990) "The basement complex of the Eastern Desert and Sinai." The Geology of Egypt. Said, R., ed. A.A. Balkema Publishers: Brookfield, VT. pp. 175-184.

Freyberger, R. (1993) “The Duke of Hamilton’s Porphyry Tables.” Antiques, 348-352.

Hassan, M.A. and A.H. Hashad. (1990) "Precambrian Egypt." The Geology of Egypt. Said, Rushdi, ed. A.A. Balkema Publishers: Brookfield, VT. pp. 201-245.

Hutton, E. (1950) The Cosmati: The Roman Marble Workers of the XIIth and XIIIth Centuries. Routledge & Kegan Paul Ltd.: London. pp. 7-28.

Kahler, H. (1967) Die Hagia Sophia. Gebr. Mann Verlag: Berlin. pp. 35, Ab. 39.

Le Maitre, R.W. ed. (1989) A Classification of Igneous Rocks and Glossary of Terms. Blackwell Scientific Publications: Oxford. pp. 107.

Maxfield, V. and D.P.S. Peacock (1996) “Fieldwork, 1995-6.” The Journal of Egyptian Archaeology, 82, 15-19.

Maxfield, V. and D.P.S. Peacock (1998) “Fieldwork, 1997-8.” The Journal of Egyptian Archaeology, 84,

16-20.

Meshref, W.M. (1990) "Tectonic Framework." The Geology of Egypt. Said, R., ed. A.A. Balkema Publishers: Brookfield, VT. pp. 113-155.

Meyer, C. (2001) "Bir Umm Fawakhir: Insights into Ancient Egyptian Mining". JOM, 49, 64-68. The Minerals, Metals & Materials Society: Warrendale, PA. Online 3 December 2001. http://www.tms.org/pubs/journals/JOM/9703/Meyer-9703.html

Online Encyclopedia of Roman Emperors. (2001) http://www.roman-emperors.org/impindex.htm Online December 1, 2001.

Peacock, D.P.S. (1997) “Charlemagne’s black stones: the re-use of Roman columns in early medieval Europe.” Antiquity, 71, 709-715.

Peacock, D.P.S. (1995) “The Passio Sanctorum Quattuor Coronatum: a petrological approach.” Antiquity, 69, 362-368.

Trengenza, L.A. (1955) The Red Sea Mountains of Egypt. Oxford University Press: Oxford, New York. pp. 2, 44, 80, 94-95, 109, 112.

Wharton, A.J. (1995) Reconfiguring the Post-Classical City. Cambridge University Press: Cambridge. pp. 113.

Appendix 1: Pictures of Rocks at Mons Porphyrites

A: (left) Black Porphyry hand specimen collected and scanned (Credit: Theresa Diehl).

B: (right) Red Porphyry hand specimen collected and scanned (Credit: Theresa Diehl).

C: Imperial Purple Porphyry hand specimens collected and scanned (Credit: Theresa Diehl).

D: Imperial Purple Porphyry blocks at the porphyry quarry (Credit: Theresa Diehl)

E and F: (left and right) Two sides of a granite fragment from the porphyry quarry collected and scanned (Credit: Theresa Diehl).

Appendix 2: Pictures of the Red Sea Mountains and Mons Porphyrites

A: Eastern Desert; Red Sea Mountains. Looking away from the Red Sea (Credit: Theresa Diehl)

B: From the wadi, the quarry. (Credit: Catie Morgan).

C: (above) Rugged terrain in wadi (Credit: Catie Morgan)

D: Large blocks at the top of the slope that could be quarried porphyry (Credit: Jon Moskaitis)