Mineral Fingerprinting of Egyptian Siliceous Sandstones and the Quarry Source of the Colossi of Memnon
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GEOLOGICAL SURVEY OF NORWAY SPECIAL PUBLICATION n 12 Mineral fingerprinting of Egyptian siliceous sandstones and the quarry source of the Colossi of Memnon Robert W.O’B. Knox1, Rainer Stadelmann2, James A. Harrell3, Tom Heldal4 and Hourig Sourouzian2 1170 Main Street, Asfordby, Leicestershire, England, LE14 3TT. 2German Archaeological Institute, 31 Abu el-Feda, 11211 Cairo-Zamalek, Egypt. 3Department of Environmental Sciences, University of Toledo, Mail Stop #604, 2801 West Bancroft St., Toledo, Ohio 43606-3390. 4Geological Survey of Norway, 7491 Trondheim, Norway. E-mail: [email protected] The two colossi that stood before the first pylon of the mortuary temple of Amenhotep III at Thebes (the Colossi of Memnon) are composed of single blocks of siliceous sandstone or quartzite, similar to that occurring in quarries near Cairo (Gebel Ahmar) and Aswan (Gebel Gulab–Gebel Tingar). In this study, mineral fingerprinting, using the method of heavy-mineral analysis, points conclusively to a Gebel Ahmar source for the two Colossi. It also identifies Gebel Ahmar as the source for the two quartzite colossi associated with the second pylon and for fragments of quartzite statues that previ- ously stood in the peristyle court. The study has further revealed a contrast in mineral composition between the two northern colossi and the two southern colossi, indicating that they were extracted from different parts of the Gebel Ahmar quarry complex. Introduction ceous sandstone (quartzite). The block tonnes (Sourouzian et al. 2006, p. 349). that forms the southern colossus is to- They were erected in front of a large brick The two colossal seated statues of Amen- day about 14 m high (Sourouzian et pylon at the entrance of the mortuary hotep III, popularly known as the Co- al. 2006, p. 325), but would once have temple of Amenhotep III, built during lossi of Memnon, are the most striking included a double crown of Upper and the 18th Dynasty of the New Kingdom features of ancient Thebes on the west Lower Egypt. Together with their pedes- (between 1390 and 1353 BC). bank of the Nile at Luxor (Figure 1). tals, both statues are estimated to have Each of the seated figures of Amen- Both statues were originally made of stood 21 m or 40 Egyptian cubits high hotep III is flanked by standing represen- monolithic blocks of brown to red sili- and to have weighed some 750 metric tations of the king’s mother Mutemweja Knox, R.W.O’B., Stadelmann, R., Harrell, J.A., Heldal, T. and Sourouzian, H. (2009) Mineral fingerprinting of Egyptian siliceous sandstones and the quarry source of the Colossi of Memnon. In Abu-Jaber, N., Bloxam, E.G., Degryse, P. and Heldal, T. (eds.) QuarryScapes: ancient stone quarry landscapes in the Eastern Mediterranean, Geological Survey of Norway Special Publication, 12, pp. 77–85. 77 n ROBERT W.O’B. KNOX, RAINER STADELMAnn, JAMES A. HARRELL, TOM HELDAL And HOURIG SOUROUZIAN on the north sides and of Queen Tiye on was not completed, however, perhaps as reported the occurrence of quartzite at the south sides. On each statue a figure a result of the death of the emperor. A several localities along the Nile Valley of a princess, whose name is lost, once unintended result of the project was the (see Heizer et al. 1973, p. 1221), it is stood between the legs of the king. The silencing of the ‘voice of Memnon’. now clear that true quartzite is restricted thrones are decorated by Nile gods tying The rock used to form the Colossi of to Gebel Ahmar, near Cairo, and the the heraldic plants of Upper and Lower Memnon is technically known as ‘sili- Aswan area (Harrell 2002, Harrell and Egypt, thereby representing the uniting ceous sandstone’, ‘silicified sandstone’ or Madbouly 2006) (Figure 2). At Aswan, of the land of Egypt under the reign of ‘orthoquartzite’, but Egyptologists have quartzite was extracted from the quarry Amenhotep III. long referred to it simply as ‘quartzite’ complex at Gebel Gulab and Gebel Tin- A devastating earthquake in the year and it is this terminology that is used gar on the west bank of the Nile (Heldal 27 BC may have caused the broad fissure here. It must be kept in mind, however, et al. 2005) and from quarries near Wadi still visible today in the northern Mem- that the geological term ‘quartzite’ usual- Abu Aggag on the east bank (Harrell and non Colossus and the collapse of the ly refers to a metamorphic rock whereas Madbouly 2006). upper part of statue. The colossus sub- in this case it is applied to one that is en- Early discussion on the source of the sequently became famous for producing tirely sedimentary. Quartzite, which was Memnon quartzites focussed on the in- a lamenting sound, apparently produced prized for its durability and distinctive terpretation of Pharaonic inscriptions by warmth from the rising sun acting on colouration, was widely used by the an- and on the logistics of transporting such early morning humidity within the fis- cient Egyptians for small to colossal stat- large blocks from distant quarry sources. sures. Greek visitors regarded this as a uary, sarcophagi, naoi (shrines), offering In a review of the existing literature, Sta- greeting of the Ethiopian hero Memnon tables, stelae, architectural elements (es- delmann (1984) concluded that Gebel (slain by Achilles at Troy) to his divine pecially door frames and internal tomb Ahmar was definitely the source of the mother Eos. More than a hundred in- linings), and occasionally barque shrines Memnon quartzites. Studies on the geol- scriptions in Greek and Latin attest to and obelisks. ogy and geochemistry of the quartzites the miraculous phenomenon of the early The quarry source of the Mem- have led to diverging opinions on their morning lamentations. During his visit non quartzite blocks has long been the quarry provenance, however. to Thebes in AD 200, Septimius Severus subject of discussion, as summarised Geological investigations initially resolved to restore the colossus, using by Varille (1933), Heizer et al. (1973), focussed on the possibility of distin- large blocks of sandstone believed to have Stadelmann (1984) and Klemm et al. guishing between the Cairo and Aswan come from quarries at Aswan. The work (1984). Although earlier authors have quartzites on the basis of their physical Figure 1. The Colossi of Memnon on the west bank of the Nile at Luxor. 78 MINERAL FIngERPRINTIng OF EgYPTIAN SILICEOUS SAndsTONES And THE QUARRY SOURCE OF THE COLOssI OF MEMNON n ly crystalline quartz) being present only ites being consistently more rounded at Gebel Ahmar (Aston et al. 2000, p. than those of the Aswan quartzites. 53). Since the majority of the sandstones Because of the difficulty (as then lack pebbles, however, this distinction is perceived) of distinguishing between the of only limited applicability. two quartzites by conventional petrolog- Another distinction that has been ical means, Heizer et al. (1973) proposed made between the two quartzites con- that a better approach would be to study cerns the nature of the silica cement, their geochemistry. Using the then inno- which occurs in two forms. One type of vative technique of neutron activation, cement, known as ‘syntaxial quartz over- they showed that the Cairo and Aswan growth cement’, is composed of relative- quartzites differed in their contents of ly large quartz crystals that have grown europium (Eu) and iron (Fe), and used in crystallographic continuity with the this difference to identify a Cairo source individual detrital quartz grains that they for the Memnon statues but an Aswan surround (see Klemm and Klemm 2008, source for the blocks used in the Roman fig. 347). The other type of cement, here repairs of the late 2nd or early 3rd century referred to as ‘microcrystalline quartz AD. This conclusion was also supported fringe cement’, is composed of clusters by a multivariate statistical analysis of of small quartz crystals that radiate out- Heizer et al.’s (1973) data by McGill and wards from the surface of the sand grains Kowalski (1977). A more comprehensive (see Klemm and Klemm 2008, fig. 334). data set was subsequently published by Shukri (1954) recognised both types of Bowman et al. (1984) and Stross et al. cement at Gebel Ahmar and said the (1988). Their findings, summarised in fringe cement varies from normal to Figure 3, reaffirmed those of Heizer et Figure 2. Location map. chalcedonic quartz. Niazi and Loukina al. (1973). A separate geochemical study (1987) also reported secondary chal- by Klemm and Klemm (1993, see also cedony (and opal) in the Gebel Ahmar Klemm and Klemm 2008) showed that and petrological characteristics. This ap- sandstone and attributed this kind of the Cairo and Aswan sandstones could proach seemed promising in view of the silicification to precipitation from hy- be distinguished by their differing con- marked difference in age between the drothermal solutions of volcanic origin. tents of a wide range of elements (Co, two deposits, with the Cairo quartzites Klemm and Klemm (1993, 2001, 2008) Fe, Mn, Pb, Rb, Sr, Zn) (Figure 4) and being of mid-Tertiary age (Oligocene, state that the fringe cement is character- used these differences to identify an As- ca. 30 Ma) and the Aswan quartzites of istic of the Cairo sandstones and that wan source for the Memnon quartzites. Late Cretaceous age (Turonian, ca. 90 quartzites lacking it must therefore have The two geochemical studies thus came Ma). However, the standard geological come from Aswan. Conversely, Aston to diametrically opposed conclusions, techniques of field examination, grain- et al. (2000, p. 53) state that although with both sets of data plots seemingly size analysis and thin-section analysis fringe cement is indeed present at Gebel providing conclusive support for their failed to identify reliable distinguishing Ahmar, the dominant cement is of the respective interpretations.