ARTIFICIAL OR NATURAL ORIGIN OF HEMATITE‐BASED RED PIGMENTS IN ARCHAEOLOGICAL CONTEXTS: THE CASE OF RIPARO DALMERI (TRENTO,ITALY)

This study concerns those crystallographic and microstructural features that can provide indications on the actual origin of red pigments based on hematite (Fe₂O₃). The main features of natural and artificial hematite are recalled and used to discuss the results obtained from the characterization of red‐ochre samples coming from the Palaeolithic site of Riparo Dalmeri, a rock‐shelter located in northeastern Italy, dated to 13 000 cal. bp , and notorious for the presence, among the other finds, of red‐painted calcareous stones. Painting and the treatment of leather and hides obtained from the intensive hunting activity were the main uses of the hematite‐based red‐ochres at Riparo Dalmeri. It turns out that hematite was mostly obtained from the thermal treatment of goethite, which, unlike hematite, was and still is widely available in the neighbourhood of the site.     

Coloured Prints of the 16th Century: Non‐Destructive Analyses on Coloured Engravings from Albrecht DÜrer and Contemporary Artists

Qualitative investigations of pigments and dyes using micro X‐ray fluorescence spectrometry (micro‐XRF) and visible spectrophotometry (VIS) are suitable non‐destructive methods for the characterization of different colorants in art objects. In this study, several rare coloured engravings from the work of Albrecht Dürer—and, in addition, from the work of Cornelis Cort, Servatius Raeven and Johannes Sadeler—were investigated. The analyses result in specific palettes of colours that were used by different artists or in different workshops for the coloration of engraved images. Starting from these different palettes, it is possible to distinguish coeval colorations that were added in the 16th century from those that were carried out at a later date (e.g., the 19th century).     

DISCOVERY AND CHARACTERIZATION OF AN UNKNOWN BLUE‐GREEN MAYA PIGMENT: VESZELYITE*

Blue‐green mosaic and polychrome masks and funerary offerings from the royal tombs of Calakmul, Mexico, were analysed by scanning electron microscope equipped with energy dispersive X‐ray spectroscopy (SEM‐EDS), X‐ray diffraction (XRD), and particle induced X‐ray emission (PIXE). This led to the first identification of the use of veszelyite, a rare hydrated copper‐zinc phosphate, as green pigment. Analyses of a geological sample of this mineral have been done to confirm the characterization of this Mayan pigment, which might help determine pre‐Columbian trade routes of precious and luxury objects in the ancient Maya Classic period (ad 250–800).     

RED PALAEOLITHIC PIGMENTS: NATURAL HEMATITE OR HEATED GOETHITE?*

Yellow goethite (α-FeOOH) and red hematite (α-Fe₂0₃) were used as pigments by Palaeolithic painters. When heated, goethite dehydrates and transforms to hematite Archaeologists wonder whether prehistoric people knew of this property and used it. We present a way to distinguish heated goethite from natural hematite. The methods used are X-ray diffraction and transmission electron microscopy. A double ‘signature’, namely selective broadening of diffraction reflections and porous nanostructure, is evidenced in heated goethite. Coupled with mineralogical associations, this allows us to establish a procedure to investigate the natural or artificial origin of hematite samples. Applied to the Palaeolithic site of Troubat, it reveals no difference between the Magdalenian and Azilian cultures concerning the heat-treatment of pigments; an area specializing in heat-treating pigments, may, nevertheless, have existed inside the cave, which would indicate that heating wax deliberate.     

Advances in Polychrome Ceramics in the Islamic World of the 12th Century AD

As part of a multidisciplinary programme of research on Islamic glazed pottery, the development of polychrome decoration during the 12th century AD has been investigated by examining polished sections through glazed pottery in an analytical scanning electron microscope. The two main decorative techniques used were underglaze and overglaze painting. The results suggest that true underglaze decoration, involving the application of pigment without any associated slip, was first developed in Syria, from where it spread to Iran, on to China and ultimately across wide areas of the world. In contrast, the overglaze technique used on mina'i ware was both very short‐lived and confined to Iran. The analytical results suggest that the probable explanation for this was the technical problems associated with maturing the overglaze paint and the consequent risk of unsatisfactory products.     

COLOURED OPAQUE GLASS BEADS OF THE MEROVINGIANS*

Monochrome coloured opaque glass beads of the Merovingians have been examined by different analytical methods. A large number of mostly unprepared beads have been measured by X‐ray fluorescence analysis. X‐ray diffraction was used for the identification of the crystalline colouring and opacifying pigments, and electron probe micro‐analysis as well as scanning electron microscopy were applied to study the composition and the microstructure of a white, brown, green, orange and yellow glass bead. After subtracting the content of colouring oxides of the glass beads and normalizing the residual values to 100% an identical soda‐lime‐glass matrix was obtained. The origin of the colouring metal oxides is discussed.     

THE ORIGIN AND GEOCHEMICAL CHARACTERIZATION OF RED OCHRES FROM THE TITO BUSTILLO AND MONTE CASTILLO CAVES (NORTHERN SPAIN)*

Ochres were the most common source materials for pigments used in Palaeolithic rock art paintings. This work analyses the petrographic and geochemical signatures of different ochre samples from outcrops inside Tito Bustillo Cave and the Monte Castillo Caves using the most common techniques (petrography, XRD, SEM–EDS and ICP–MS) in archaeological pigment characterization studies. The results obtained permit the identification and characterization of the different source ochre types and, furthermore, allow the establishment of mineralogical and geochemical proxies for the study of questions related to ochre characterization, formation processes and provenance.     

THE CHARACTERIZATION OF PAINTS AND WATERPROOFING MATERIALS FROM THE SHIPWRECKS FOUND AT THE ARCHAEOLOGICAL SITE OF THE ETRUSCAN AND ROMAN HARBOUR OF PISA (ITALY)*

This work presents the results of a diagnostic survey on the shipwrecks from the archaeological site of the ancient harbour of San Rossore (Pisa, Italy). The original waterproofing, caulking and painting materials were characterized by Fourier transform infrared spectroscopy (FTIR), gas chromatography – mass spectrometry (GC–MS), energy‐dispersive X‐ray microanalysis (EDX) and X‐ray diffraction (XRD). The major constituents of the waterproofing and caulking materials detected on the planks were tricyclic abietanes showing a high degree of aromatization. These compounds are indicative of a pitch obtained from the wood of trees of the Pinaceae family. The analysis of the organic components of the paint samples revealed diterpenoid acids characteristic of Pinaceae resins together with linear long‐chain alcohols and fatty acids, highlighting the presence of beeswax. Noticeably, the characteristic odd carbon number alkanes that are normally present in beeswax were not detected. The EDX and XRD analyses showed that hematite, calcite, cerussite and kaolinite were employed as pigments to paint the ships’ hulls.     

The Improved Lns Pixe‐Alpha Portable System: Archaeometric Applications*

The possibilities presented by the improved portable PIXE system are discussed. Examples are given of applications in the cultural heritage field, and in particular in the characterization of pigments and silver patina on ancient Roman coins. The limitations of the system are also discussed.     

Pigments and Plasters Discovered in the House of Diana (Cosa,Grosseto, Italy): An Integrated Study Between Art History,Archaeology and Scientific Analyses*

The pigments and the plasters of the Roman frescoes discovered at the House of Diana (Cosa, Grosseto, Italy) were analysed using non‐destructive and destructive mineralogical and chemical techniques. The characterization of both pigments and plasters was performed through optical microscopy, scanning electron microscopy and electron microprobe analysis. The pigments were identified by Raman spectroscopy and submitted to stable isotope analysis. The results were integrated with the archaeological data in order to determine and reconstruct the provenance, trade patterns and the employment of the raw materials used for the elaboration of the frescoes.