
Roberto GiustettoUniversity of Turin | UNITO · Dipartimento di Scienze della Terra
Roberto Giustetto
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Publications (61)
The Bilsk archaeological complex comprises the remains of many structures associated with an impressive Iron Age fortified site and extends over a vast area in central-east Ukraine. Its importance is marked by the presence of apparently imported objects, including some vitreous ones (represented mainly by glass and faience beads), which provide res...
Defendente Ferrari, one of the most important painters of the Piedmontese Renaissance, was extremely active in the early 16th century. His Madonna with Child and two Saints (1505–1510 ca.), which was originally located in the Collegiate Church of Carmagnola (Turin province, Italy) now in the collections of Palazzo Madama - Museo Civico d’Arte Antic...
Colorimetric evaluation was applied on archaeological pottery from the ancient port city of Adulis in the Red Sea coast of Eritrea. Pottery samples belong to the Ayla-Aksum typology, Late Roman Amphora 1 and dolia classes, which had never been analyzed by means of this approach. The survey consisted of colorimetric measurements from different parts...
The greenstone industry of Valgrana/Tetto Chiappello was studied with an archaeo-typological and mineral/petrographic approach (functional study, XRPD, polarized light microscopy and SEM-EDS), to infer the provenance of the raw materials and the role of this site in the general greenstone circulation during Neolithic. Most artifacts (mainly cutting...
The damages caused by the growth of gypsum crusts on calcareous substrates are well known. Sulfation of stones such as marble and travertine-used in constructions and Cultural Heritage-implies a structural and aesthetical weathering that leads, in time, to flaking, spalling, and disruption. The effects of the initial gypsum growth and development w...
The damages caused by the growth of gypsum crusts on calcareous substrates are well known. Sulfation of stones such as marble and travertine used in constructions and Cultural Heritage implies a structural and aesthetical weathering that leads, in time, to flaking, spalling and disruption.The effects of the initial gypsum growth and development wer...
The polished stone industry of Chiomonte (Piedmont
region, northwestern Italy), dating back to the middle to late Neolithic,
has been studied with a multi-analytical approach, including mineralogical,
petrographic and morpho-typological issues, with the aim of providing
information about the sources of the raw materials and determining
the function...
In 1989 an ancient burial consisting of a skeleton and a few objects was discovered at the Monte dei Cappuccini Monastery, in Torino (Italy). Anthropological analysis of the skeleton revealed that it belonged to a young man, and the archaeometric characterization of the objects suggested that most of them are compatible with the Medieval period. As...
An unusual occurrence of asbestiform sepiolite, filling veins in the antigorite serpentinites of the Voltri Unit exposed in a borrow pit (nowadays reclaimed) in the Deiva forest, near Sassello (NW Italy), was probed with an in-depth analytical approach aimed at studying its crystal-chemistry and structure and evaluating its possible hazards for hum...
Appendix A. Supplementary data
Analytical techniques based on luminescence properties of materials have proved to be useful in the study of artistic and archaeological materials. For example, iono-luminescence (IL), in conjunction with ion beam analysis (IBA) techniques, and cathodoluminescence (CL), coupled with optical microscopy or scanning electron microscopy (SEM), are impo...
An archaeometric survey allowed to understand the causes of an atypical ongoing decay, manifested by a 19th century fresco of an unknown artist titled ‘The divine adoration of King St. Louis IX’, held in the Church of ‘San Francesco dei Cappuccini’, in Racconigi (Northwestern Italy). The wall painting suffered of a diffuse darkening, principally af...
The overgrowth of gypsum (CaSO4·2H2O) on calcite (CaCO3), used as a substrate, has been obtained in order to verify the hypothesis of a crystallographic fit between the two phases. Lattice coincidences show that many orientations of gypsum with respect to calcite can occur. Experimentally, only two among these are fulfilled during the early stages...
An extremely stable hybrid composite, useable as a pigment in the Cultural Heritage and Materials Science fields, can be obtained by grinding and heating 2wt% methyl red with palygorskite, a fibrous microporous clay mineral. Dye molecules are incorporated within the clay nanotunnels and/or superficial grooves, partly sheltered from the external env...
An in-depth scientific survey revealed the deterioration mechanisms affecting the ‘Santa Maria della Stella’ church in Saluzzo, Italy, where various salt crystallization processes are strongly damaging the building materials and artworks. Rainwater seepage permeates the vault and interior, causing: (1) epsomite growth as interstitial columnar cryst...
High-pressure (HP) meta-ophiolites-usually termed 'greenstones' by archaeologists-were used in the Neolithic to produce polished stone implements all over Western Europe. Their accurate petrographic characterization may help to infer the provenance of the raw materials, thus contributing to reconstruct the migratory routes of our ancestors. The lit...
The thick gypsum deposits formed in the Mediterranean Basin during the Messinian salinity crisis incorporate dense mazes of fila-mentous fossils, which were interpreted as algae or cyanobacteria, thus pointing to a shallow-marine subtidal or intertidal environment. The data presented here reveal that these filaments represent remains of colorless,...
When Conservation scientists casted a glance at the inner cupola of the ‘Beata Vergine del Pilone’
Sanctuary in Polonghera (Italy), they scarcely could believe their eyes. Some 18th Century frescoes looked
as if an unknown vandal covered the skin of religious characters with brown paint. This disquieting
transfiguration was due to a viscous patina,...
Abstract: The Church of “Santa Maria della Stella” examined in this work, is a part of a complex erected in a time ranging from the beginning of 17th to the end of 19th century. The pristine religious building was constructed in 1611 to host the monastery of the “Clarisse” Nuns, previously housed in a nearby village, Rifreddo. Later, approximately...
A great number of prehistoric stone implements from Western Europe are made of high-pressure (HP) metamorphic lithotypes, such as Na-pyroxenites and fine-grained eclogites. These rocks represent minor “accessory” lithologies that occur as either small primary outcrops or secondary clastic deposits derived from erosion of the former. Due to their sc...
An atypical asbestiform sepiolite occurrence with exceptionally long fibres wrapped by a sheath of aliphatic hydrocarbons was found in the Gressoney Valley (Italian Western Alps) while monitoring asbestos presence in outcrops of serpentinite rocks. Microscopic and Fourier transform infrared analyses proved that these fibres, apparently up to severa...
Palygorskite is a microporous clay mineral with several important applications, including use as a dye nanoscaffold, due to its ability to incorporate apt guest molecules and form exceptionally stable composites. Such a property covers widespread fields of interest, from pottery pigments to light harvesting. In all these applications, the stability...
The recognition of peculiar laminated layers atypically rich in a biogenic intrabasinal component in the mudstone intervals from the Messinian (late Miocene) Primary Lower Gypsum unit (5.97-5.60 Ma) of the Piedmont basin (NW Italy) provides information on the palaeoenvironmental evolution at precessional insolation maxima. These cyclic layers consi...
The performed survey paved way for a restoration intervention, achieved by delicately dry-cleaning the frescoes surface and applying a proper biocide which allowed an effective biofilm extirpation while preserving the vividness of the residual pigmented layers (Figg. 7 and 8). The effectiveness of the intervened restoration is guaranteed by these f...
Prehistoric pottery decorated with incisions or impressions filled with white and seldom coloured inlays is well documented in the archaeological literature, but the related in-depth archaeometric studies are sporadic. 43 decorated ceramic shards, dating from the Neolithic to the Bronze Age, and an Iron Age fibula from the archaeological site of Ca...
This study reports on the geochemical and mineralogical characterization of a lateritic profile cropping out in the Balkouin area, Central Burkina Faso, aimed at obtaining a better understanding of the processes responsible for the formation of the laterite itself and the constraints to its development. The lateritic profile rests on a Paleoprotero...
A pristine magnetite (Fe3O4) specimen was studied by means of Neutron Powder Diffraction in the 273–1,073 K temperature range, in order to characterize its structural and magnetic behavior at high temperatures. An accurate analysis of the collected data allowed the understanding of the behavior of the main structural and magnetic features of magnet...
An unusual occurrence of palygorskite was found near Montestrutto, lower Val d'Aosta (Italy), within an eclogite-facies leucogneiss of the Sesia-Lanzo zone. Under the optical microscope the mineral appears as a felt of fibres hundreds of μm long and a few μm thick. SEM observation proved each filament to be a bundle of smaller but remarkably long f...
Maya Blue pigment forms through heating-induced encapsulation and bonding of indigo in microporous clays, namely, palygorskite or sepiolite. Stabilizing host/guest interactions in a sepiolite-based Maya Blue were investigated by means of vibrational and NMR spectroscopies and proved to be H-bonds formed between indigo reactive groups and the clay s...
Palygorskite is a clay mineral whose structure is crossed by nano-channels (0.64 x 0.37 nm) filled by H2O and exchangeable ions. When mixed and heated with indigo it forms Maya Blue, a well-known pigment in which the guest dye is encapsulated and bound within the hosting matrix tunnels, conferring the compound its astounding stability. Sorption pro...
Maya Blue is an artificial pigment used in Pre-Columbian America, renowned for its chemical stability. The pigment can be considered a precursor of modern inclusion compounds as a hosting microporous clay (palygorskite or sepiolite) shelters the guest indigo dye (<= 2 wt%) within its micro-channels. While most papers on Maya Blue are focused on the...
Sepiolite is a fibrous clay mineral which, together with palygorskite, is an end-member of the palygorskite–sepiolite polysomatic series. Both palygorskite and sepiolite are renowned in Cultural Heritage studies because when properly complexed to the indigo dye they form Maya Blue, a synthetic blue pigment used in Pre-Columbian America which is fam...
A large number of polished stone implements from Palaeolithic to Bronze Age sites of Northern Italy and Southern France are made of high-pressure (HP) metamorphic rocks (eclogite and related rocks), mainly consisting of Na-pyroxene (jadeite to omphacite) from the metamorphic belt of the Western Alps. The standard archaeometric study of prehistoric...
The ancient Maya combined skills in organic chemistry and mineralogy to create an important technology - the first permanent organic pigment. The unique color and stability of Maya Blue can be explained by a new model where indigo dye fills the grooves present at the surface of palygorskite clay, forming a hydrogen bonded organic/inorganic complex....
Maya Blue, a synthetic pigment produced by the ancient Mayas in pre-Columbian America, is the combination of a fibrous clay (palygorskite) and an organic blue dye (indigo). The main features of the structure of Maya Blue are already known, although the specific interactions occurring between clay and dye have yet to be completely explained. The det...
Maya Blue pigment, used in pre-Colombian America by the ancient Mayas, is a complex between the clay palygorskite and the indigo dye. The pigment can be manufactured by mixing palygorskite and indigo and heating to T > 120 degrees C. The most quoted hypothesis states that the dye molecules enter the microchannels which permeate the clay structure,...
Palygorskite is a Mg-rich fibrous clay, present in nature as a mixture of two intricately intertwined polymorphs monoclinic (C2/m) and orthorhombic (Pbmn) - characterized by the presence of channels along Z-axis, filled by weakly bound zeolitic water. A neutron powder diffraction study was carried out by full Rietveld refinement on a deuterated sam...
Maya Blue, a synthetic pigment produced by the ancient Mayas, is a combination of a specific clay, palygorskite (or sepiolite), containing large channels in the crystal structure and the organic dye indigo. Little is known about the interaction of the two components to give the most stable pigment ever produced. The aim of this work is to obtain a...
Preliminary results to use 14 C dating techniques on the carbon coming from indigo present in the Maya Blue pigment are reported. A preliminary solution is outlined of the several problems present.
Neolithic polished artifacts (particularly axes) are often made of "green stone", which includes serpentinite, jadeitite omphacitite and eclogite. Only the first rock can be discriminated by nondestructive density measurements. In order to determine the provenance and reconstruct the trading path, a more precise rock characterization is needed. For...