COMPOSITIONAL CHARACTERIZATION OF FRENCH LIMESTONE: A NEW TOOL FOR ART HISTORIANS*

Limestone from quarries known to medieval craftsmen and from the monuments they built and embellished, as well as from carvings now in museum collections, has been characterized by neutron activation analysis. Specimens from 38 quarries in the Lutetian and Jurassic limestone formations of France and from sculptures in American and French museums have been tested, and the results have been compiled in a data base to which art historians may refer when attempting to determine provenance for sculptures. Multivariate statistical analysis of concentration data shows stone from a particular quarry in the Paris basin to be compositionally homogeneous and distinguishable from other quarries in the same formation. The same approach to data related to quarries near the Burgundian abbey of Cluny finds general agreement between classifications based on compositional and on petrographic data, but the number of samples available for analysis at the time of writing was insufficient to achieve the finer distinctions reported for the Paris basin.     

AN ANALYTICAL STUDY OF IBERIAN IRON AGE STONE SCULPTURES AND THEIR SURFACE MARKS

The Archaeological Museum of Jaén's sizeable collection of Iron Age sculptures, dating from the fifth century bce , were all found at Cerrillo Blanco de Porcuna, a site in the Spanish province of Jaén. The collection comprises over 40 statues and hundreds of fragments. Incisions recently identified on some of these sculptures have been interpreted as sculptors' marks. The present archaeometric study, conducted with a 3D roughness meter, showed that the marks on several of the sculptures analysed were made with the same type of tool and the same engraving technique. While the graphological differences denote different authorship, they would appear to have been made in the same workshop. The morphological differences observed in the lines analysed on other sculptures are interpreted to indicate the use of other types of tools and engraving techniques.     

TOWARDS A QUANTITATIVE PETROGRAPHIC DATABASE OF KHMER STONE MATERIALS—KOH KER STYLE SCULPTURE

A comprehensive quantitative petrographic database of sandstones used by the Khmers for sculptural purposes would be a helpful tool for archaeologists, museum curators and others interested in pursuing research on early stone usage, geological source and provenance. Towards that end, this paper presents quantitative petrographic analysis of stone materials used in the production of some free‐standing sculptures and architectural elements in the Koh Ker style of the 10th century from the collections of the National Museum of Cambodia and The Metropolitan Museum of Art. These materials are compared to samples from the quarry of Thmâ Anlong near the foothills of the Phnom Kulen, Sieam Reap province. Primary and secondary detrital modes and key grain‐size parameters are used to identify three sandstone types. The free‐standing sculptures are carved from feldspathic arenite and feldspato‐lithic to litho‐feldspathic arenite. Finely carved lintels are worked from a quartz arenite, which is significantly richer in quartz grains and of a finer grain size. The geological source of the two other lithotypes will have to await detailed geological survey of the Koh Ker area accompanied by petrographic study of selected samples from documented quarries. The significance and potentiality of quantitative petrographic study of Khmer stone materials are shown in supporting and integrating archaeological investigations in South‐East Asia.     

BLACK AND RED GRANITES IN THE EGYPTIAN ANTIQUITY MUSEUM OF TURIN: A MINERO‐PETROGRAPHIC AND PROVENANCE STUDY

A recent project to investigate the stone artefacts preserved in the Egyptian Antiquity Museum of Turin has been undertaken, with the aim of supplying their systematic classification and suggesting the provenance site of the original raw materials. This paper focuses on seven sculptures dating back to the New Kingdom (18th–19th Dynasties): the statue of Ramses II, three of the 21 sculptures of the goddess Sekhmet, the statue of the goddess Hathor, the Ram‐headed Sphinx and the sarcophagus lid of Nefertari. Petrographic observations have shown that all the sculptures are made of granitoid rocks, with variable composition from granite to granodiorite and tonalite. The observation of strong macroscopic analogies with the so‐called black and red granites outcropping in the Aswan area has suggested a common origin of all the raw materials used for their manufacture. In order to verify this provenance hypothesis, several samples were collected in the Aswan quarry districts. According to results of a minero‐petrographic and geochemical comparison between the statues and the Aswan quarry samples, it was possible to identify the source area of the stone sculptures and finally to highlight the importance of an archaeometric approach to the solution of archaeological problems.     

THE ROMANESQUE FRIEZE AT LINCOLN CATHEDRAL (ENGLAND)—PRIMARY OR SECONDARY INSERTION? MAGNETIC CONSIDERATIONS*

The current debate about the age of the Romanesque frieze of Lincoln Cathedral weighs archaeological evidence against art history. On the one hand, the panels appear to be an integral part of the original Norman structure built by the first bishop (AD 1072–92). However, on grounds of style and artistic comparisons, art historians argue for a later installation during the restoration of AD 1141–6. In order to determine when the panels were stabilized in the cathedral, we used a new method that measures their degree of remagnetization by the earth's magnetic field since they were quarried. The longer that masonry remains stabilized in a given orientation, the greater its viscous remagnetization. Viscous remanent magnetization dating has previously been successful with this particular type of limestone masonry. Our results lend support to the view that the panels were installed in the early 1140s.     

A BRONZE SCULPTURE ATTRIBUTED TO LOUIS-SIMON BOIZOT AND PLATINUM COATING METHODS

During the examination of the sculpture of Medea Rejuvenating Aeson attributed to Louis-Simon Boizot (1743–1809), X-ray fluorescence analysis revealed, surprisingly, that the outer surface of the brass cast was patinated with platinum. Research into the history of platinum coating methods revealed that chemical techniques for the deposition of platinum from solution were in use before the advent of electroplating. Some experimental work to replicate the patination technique of electrochemical replacement plating of platinum based on recipes from the nineteenth century is described. The technical evidence suggests that a late eighteenth-century date for the sculpture is reasonable.     

In the Steps of William the Conqueror: Neutron Activation Analysis of Caen Stone*

Quarries in the Bathonian stone formation surrounding Caen produced high‐quality limestone for medieval churches in northern France and southern England and for their sculptural decoration. To investigate compositional differences among proximate stone sources, 103 samples collected from five separate quarries were analysed by NAA. The results show Caen stone to be essentially pure calcite and relatively homogeneous, but distinction among quarries is possible by discriminant analysis. Comparing compositions of quarry samples with data in the Brookhaven Limestone Database identified the origin of stone used in masonry and sculpture at Saint‐Étienne and La Trinité, Caen, and in several museum objects.