7.1: Reading/Media

Temple ruins in Uruk, an ancient city in southern Mesopotamia. Written language is believed to have been born in Uruk as cuneiform inscription on river clays. A collection of cuneiform artefacts from Uruk and other Mesopotamian locations are examined here for their making processes and mineralogical origins. (Image by tobeytravels, Wikimedia.)

Cuneiform Writing on River Clays in Old Babylonia, 3,800 BP

Excerpts from "A synchrotron X-ray powder diffraction study of cuneiform clay artefacts" by R. Cameli Manzo, Z.J. Földi, S. Jáka-Sövegjártó, et al. npj Heritage Science 13, 605 (2025). CC

River-deposited clay as a writing medium

Excerpt: In ancient Mesopotamia, the clay provided by the Tigris and Euphrates alluvial plains (Fig. \(\PageIndex{1}\)) was used for many purposes, such as for construction and for manufacturing votive objects, and as a writing medium. Inscribed with cuneiform signs, clay artefacts record a variety of information, including administrative records, letters, medical text, and literature. A significant number of written documents date back to the so-called Ur III period (21st c. BC) because of a massive reorganization of state administration at that time. With respect to the manufacturing of tablets, authors have suggested that these artefacts were mostly sun-dried, while only a small number were intentionally fired in antiquity. Clay cones and clay bricks, inscribed with accounts of the ruler’s building activities, were supposedly baked and then placed in the foundations and walls of monumental buildings. Nonetheless, determining which artefacts were treated intentionally is difficult, given that firing was a common practice developed by museums for conservation purposes, especially from the 1950s to the early 1990s, until this treatment was deemed unnecessary in 1987 and 1993. Furthermore, historical events such as the sacking of royal archives following the siege of Nineveh in 612 BC complicate the correct determination of intentional firing as a pottery practice.

Figure \(\PageIndex{1}\): Map showing the site provenance of the 36 written artefacts considered in this study. (From Cameli Manzo et al. 2025.)

To better understand the raw material used for manufacturing these artefacts, an important method for determining the mineral composition is X-ray powder diffraction (XRPD). This technique has been implemented both invasively and non-invasively. In the cases where the analysis was destructive, a portion of the clay tablets was scratched or removed, whereas in one instance, a micro X-ray diffractometer was used to identify the main minerals in reflection geometry. Non-invasive analyses are important owing to the conservation of the artefacts and for the possibility to reproduce the experiments.

Archeological background: a case study

Clay cone 1913.131 from the MK&G collection bears a building inscription attributed to Sîn-kāšid, an Amorite ruler of Uruk in the Old Babylonian period (20–17th c. BCE) (Fig. \(\PageIndex{2}\)). The same inscription has been observed on over a hundred written artefacts, including clay cones and tablets, some discovered through scientific excavations of the remains of Sîn-kāšid’s palace at Uruk and others acquired from the antiquities market. The inscription is edited in Frayne, D. R. as no. 4.4.1.3. For a detailed list of corresponding artefacts see Frayne, D. R. 444−447. The transliteration and translation presented here follow the edition in this volume. Italics indicate Semitic elements in the Sumerian text, including the ruler’s name and the name of an Amorite tribe. The present artefact belongs to the latter category and lacks a documented excavation context. Nevertheless, given that Sîn-kāšid is known only from Uruk, the provenance of the artefact can be reliably assigned to this site. The chronological placement of Sîn-kāšid’s reign in the 19th c. BCE provides an approximate date for the object. The inscription comprises nine lines written in the ductus of Old Babylonian monumental inscriptions. The transliteration and translation of the Sumerian text inscribed on the cone are as follows:

1. ^dsuen-ka₃-ši-id / Sîn-kāšid
2. nita kalag-ga / mighty man
3. lugal unug^ki-ga / king of Uruk
4. lugal am-na-nu-um / king of the Amnānum (tribe)
5. u₂-a / provider
6. e₂-an-na / of the Eanna (temple)
7. e₂-gal / built
8. nam-lugal-la-ka-ni / his royal
9. mu-du₃ / palace

Figure \(\PageIndex{2}\): Image (right) and hand copy of the inscription (left) of clay cone 1913.131. The translation of the inscription is given above. (From Cameli Manzo et al. 2025.)

Clay cones, along with other artefacts bearing short royal inscriptions, were commissioned by rulers in connection with construction and restoration projects. These objects, which include tablets, cones, figurines, and architectural elements such as door sockets, were produced en mass in workshops and placed within buildings as part of foundation or dedicatory assemblages. Clay cones were specifically designed as decorative elements inserted into the walls. In some cases, more than a thousand cones bearing the same inscription have been preserved, underscoring the scale of their production. Once embedded in the walls, the text on their shaft remained hidden from human sight, as their inscriptions were intended for a divine audience to affirm the ruler’s piety and immortalize his achievements in the presence of the gods. Furthermore, rulers of later times were also meant to discover foundation deposits and honour previous builders and restorers with their own inscriptions. Royal inscriptions, when preserving the name of the ruler, are generally straightforward to date. In the case of Sîn-kāšid, both the dating and provenance are not problematic, as his rule is exclusively associated with Uruk. However, in many other cases, establishing a date and provenance is considerably more challenging, especially when artefacts lack a documented archaeological context or when excavation records are incomplete. Without such information, researchers must rely on internal textual features, palaeographic analysis, and comparative material to approximate the time and place of origin.

Mineralogical composition

The experiments revealed considerable variability in the mineral composition among the artefacts. A mineral identified in all the cases is quartz, given its ubiquitous abundance and high thermal stability. Feldspars were also found in all the objects, represented by the plagioclase endmember albite, whereas other studies report plagioclase or plagioclase+K-feldspar as the main feldspar phases. Clay minerals were represented mainly by illite, both in terms of distribution and abundance, whereas lower concentrations of kaolinite, chlorite and, in some instances, palygorskite were also observed. Small amounts of amphibole hornblende were found in most of the artefacts. Calcite was also highly represented, with only two samples completely missing its characteristic peaks. In these two samples, namely, a clay tablet (2023.1) and a clay cone (1913.132) from Uruk and dated to the 19th c. BC, illite and hornblende were not observed, but the zeolite analcime was present. Other carbonates, such as aragonite and dolomite, were observed in some of the samples. Gypsum, found only in one clay cone, 1913.128 (Lagash, 22nd c. BC), has been identified in a study on tablets from Umma, Dilbat, Larsa, Ur, Babylon, Uruk, Sippar, and Nippur (Ur III and Early Achaemenid periods) using micro X-ray diffraction. This mineral could form on the surface of the artefact as an alteration product. The clinopyroxene diopside was found in some artefacts in conspicuous amounts, and samples 2023.1 and 1913.132 contained up to 70 wt. % diopside according to phase quantification with the Rietveld method. Finally, we determined the occurrence of spinel-phase magnetite in a clay tablet whose envelope was from Girsu, 21st c. BC. The occurrence of magnetite in other samples is not excluded but could not be determined given that the intense peaks overlap with the diopside peaks.

Mineral content in relation to morphology, provenance and dating

The surfaces of some of the artefacts considered in this study, including clay cone 1913.130, were blackened. However, we could not identify any relevant mineral conferring this effect. Since alterations of the surface often consist of only a few atomic layers, surface diffraction methods in reflection geometry (e.g., grazing incidence) might provide greater insight into the nature of this blackening. However, such an investigation was beyond the scope of our study. Considering the individual documents according to morphology, the leg-shaped artefact displays the paragenesis of quartz, calcite, albite, aragonite, amphibole and illite (1983.286), shared with most of the other clay tablets, including their envelopes. This composition is independent of the inferred provenance for tablets belonging to the Ur III period and for the leg-shaped artefact, which dates approximately 1000 years later. The objects from the 22nd c. BC and the 19th c. BC, consisting of two tablets (2023.1 and 2023.2) and all the investigated clay cones, contain various amounts of diopside. Nonetheless, according to existing research on clay tablets from the Old Babylonian (ca. 1800 BC), Neo-Babylonian (ca. 550 BC), and Early Achaemenid (ca. 500 BC) periods and from the inferred Neo-Babylonian, pyroxene was not observed. In our study, the presence of diopside is independent of provenance and period. All the clay cones contain various amounts of diopside. This suggests a differentiation of manufacture according to the purpose of the clay cones, which confirms the description in Chiera (1938). Sufficient statistics of measurements would clarify this finding.

Clay processing

The raw starting material used for manufacturing the measured objects resulted in illitic clay or silt with various contents of chlorite, kaolinite, and palygorskite. A comprehensive study in which XRPD, FTIR, and SEM−EDX methods were performed on small samples from cuneiform tablets also revealed palygorskite-based silt with inclusions of calcite, quartz, and amphibole³. In our case, palygorskite is not the main representative clay mineral in all the objects. Instead, the main clay fraction resulted in an illitic phase. The mineral composition of some of the tablets is comparable to that of deposits along the Euphrates from Hilla (Babylon) to Basrah, Iraq, with illite, chlorite, kaolinite, and palygorskite being the major representative minerals of the clay fraction. The clay mineral contents in the sediments studied were, on average, 20%. However, in the samples considered here showing comparable mineralogy, the average clay mineral content increased to 40 wt. % after Rietveld quantification. This difference could be attributed to the variability in the mineralogy of sediments from the Mesopotamian Plain according to the area distribution and depth. Among the heavy fraction, sediments near Nasiriyah, Iraq, also contain hornblende. Compared with sediments from the Basrah area, which is closer to the Persian Gulf, there is a substantial difference, namely, the lack of gypsum–except for the small amount in one sample, possibly due to percolation and precipitation during burial—or halite in our samples derived from estuarine fluctuations.

With respect to the determination of thermal treatments, firing tests conducted on materials used in the manufacturing of ceramics in the Algarve Basin in southern Portugal attributed the occurrence of diopside to the thermal decomposition of dolomite. The findings were observed from temperatures ranging from 700–900 °C depending on the starting composition of the minerals. This pyroxene forms from either the vitreous phase derived from the decomposition of clay minerals and silicates or at the interfaces between minerals. Additionally, thermal decomposition of chlorite can lead to the formation of clinopyroxene and a spinel phase (magnetite). Our results indicate that dolomite can occur in some of the tablets in modest amounts, whereas the main carbonate comprised calcite in all the cases. To explain the high contents of diopside in artefacts 1913.132 and 2023.1, the high content of MgO available during a probable firing must be considered. In addition to dolomite, illite and chlorite are included. An important contribution to the reaction of MgO might also be derived from the thermal decomposition of palygorskite, a clay mineral containing high contents of MgO, which we observed in some cases and is found in raw materials from the Mesopotamian Plain, along the Tigris and the Euphrates. The occurrence of magnetite, together with diopside, could be determined in only one sample, and owing to its low content and peaks in the diffractogram overlapping those of the more represented diopside, whether other samples might also contain small amount following high-temperature treatment is unclear. Iraqi sediments contain small amounts of magnetite; however, magnetite is also a product of firing pottery. For this reason, it is unclear whether magnetite is derived from the sediment or a firing process.

Key Geologic Concepts:

Chemical weathering of silicates; river erosion and deposition of rock materials; clays.

Supplemental Materials:

Youtube: National Geographic: Ancient Mesopotamia 101

Youtube: The Samarians: Fall of the first cities.

Institute for the Study of Ancient Cultures, University of Chicago: Cuneiform tablets collection.