synchrotron radiation and archaeometry · radiation to the study of glasses of archaeological...
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SynchrotronSynchrotronSynchrotron RadiationRadiationRadiation andandandARCHAEOMETRYARCHAEOMETRYARCHAEOMETRY
Simona Quartieri Dipartimento di Scienze della Terra
Università di Messina
Quartieri - SILS 2006 Napoli
SynchrotronSynchrotronSynchrotron radiationradiationradiation and and and archaeometryarchaeometryarchaeometryHighly intense X-ray beams as produced at synchrotronradiation facilities, that are also highly monochromatic and have a low divergence, are highly suitable tools forexamining fragile, valuable and/or unique artefacts withminimal or no damage. We can achieve information about the major- and trace-level composition of the objects, about the chemical state of one or more atomic species that are present and/or about crystallographic phases on the materials.
Since the materials and objects encountered in the field of art-analysis, archaeology and conservation are oftencomplex in shape, covered with alteration layers and/or maybe highly heterogeneous, the use of X-ray micro beams isvery often required to allow for the measurement of localrather than bulk properties.
Quartieri - SILS 2006 Napoli
The questions that archaeologists ask more often regarding an object are:
what material is it made of (composition)
when was it made (dating)
where was it made (provenance)
how was it made (art technology)
how can we avoid its destruction (conservation)
Quartieri - SILS 2006 Napoli
AppliedAppliedApplied techniquestechniquestechniquesElemental microanalysis down to the sub-ppm level is possible bymeans of µ-XRF (X-ray fluorescence analysis).
Local chemical state determinations of selected (trace) constituentsare possible by applying XAFS and µ-XAFS (X-ray absorptionspectroscopy)
Information on the presence and nature of crystalline phases can beobtained via XRD (X-ray diffraction), which usually employ X-rayphotons with energies in the 0.5 to 30 keV range.
Alternatively, entire objects may be bathed in highly-energeticsynchrotron beams to allow high quality radiographic or tomographicimaging measurements, revealing the internal structure of theseartefacts.
Quartieri - SILS 2006 Napoli
XRD applicationsat SRA2005
Manufacturing Manufacturing cosmeticscosmetics in in ancientancient EgyptEgypt
Manufacturing Manufacturing cosmeticscosmetics in in ancientancient EgyptEgypt
Manufacturing Manufacturing cosmeticscosmetics in in ancientancient EgyptEgypt
Quartieri - SILS 2006 Napoli
Manufacturing Manufacturing cosmeticscosmetics in in ancientancient EgyptEgypt
Quartieri - SILS 2006 Napoli
artificially synthesized !
Quartieri - SILS 2006 Napoli
Quartieri - SILS 2006 Napoli
Quartieri - SILS 2006 Napoli
Mural painting representing an eagle-knight, probably a religious symbol (Cacaxtla, Tlaxcala, Mexico)
Pottery vase representing Tlàloc, the Mayan god of rain (Templo Mayor museum , Mexico).
MAYA BLUE PIGMENT[G. Chiari, R. Giustetto, G. Ricchiardi (2003) Eur. J. Mineral. 15:21-33]
G. Chiari (2005) IUCr, Firenze
Quartieri - SILS 2006 Napoli
In Mexico it was used until the end of ‘600. In Cuba it is found on walls dating 1830. It was “re-discovered” in 1849, together with the remains of the Maya civilisation.
Maya BlueMaya Blue is a synthetic pigment, produced by the Mayas probably around the VIII century AD
A bright turquoise, it was used in mural paintings, statues, ceramics, codices, and even to tint prisoners to be sacrificed.
Quartieri - SILS 2006 Napoli
Maya BlueMaya Blue is extremely stable: it can resist the attack of boiling, concentrated nitric acid, alkali and any sort of organic solvents.
Its composition and structure was a mystery for a long time. Kleber (1967) proposed a mixture of the colourless clay palygorskite and the blue organic dye indigo:
HE WAS RIGHTHE WAS RIGHT
Quartieri - SILS 2006 Napoli
PALYGORSKITE PALYGORSKITE [(Mg, Al)4 (Si)8 (O, OH, H2O)24 nH2O]
Micro-channels filled with weakly bound zeolitic H2OThe cations complete their coordination with tightly bound structural H2O
Fibrous clay (SEM image, 3520X)
Quartieri - SILS 2006 NapoliIndigo molecule
INDIGOINDIGO
The Mayas extracted it from the leaves of Indigofera suffruticosa
Quartieri - SILS 2006 Napoli
Orthorombic Palygorskite projected on (001) face
MAYA BLUE PIGMENT ?
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SR X-ray powder diffraction at GILDA beamline
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Electron Density map at the level of indigo
Indigo
Quartieri - SILS 2006 Napoli
Quartieri - SILS 2006 Napoli
MODEL OF ENCAPSULATION OF INDIGO IN THE PALYGORSKITE FRAMEWORK
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Indigo can go into the channels only if the zeolitic water is removed (130 < T < 220°C).
MAYA BLUEMAYA BLUE forms at about T = 100°C.
Even if indigo could displace water, the molecule has to break strong H bonds (≈ 1.8 Å between
indigo -C=O and structural water) to move inside the channels.
The formation of Maya Blue depends upon a very long series of highly unlikely events.
Quartieri - SILS 2006 Napoli
ThermalThermal AnalysisAnalysis of of paligorskitepaligorskite (black) (black) and Maya Blue (and Maya Blue (redred))
The water loss at 120<T<300°C (ZEOLITIC ZEOLITIC water) is the sameis the same for both palygorskite and Maya Blue.
Quartieri - SILS 2006 Napoli
The water loss at 120<T<300°C (ZEOLITIC ZEOLITIC water) is the same for both materials. It makes sense if indigo does not enterdoes not enterthe channels.
The ADSORBEDADSORBED water loss at low temperature (<120°C) is much higher for palygorskite than for MB. It makes sense if indigo occupies the grooves instead of water.
Quartieri - SILS 2006 Napoli
A new theory is needed:A new theory is needed:Indigo does not go inside the channels but Indigo does not go inside the channels but only fills the grooves all around the crystalonly fills the grooves all around the crystal
Water
Indigo
H2O
Indigo
Quartieri - SILS 2006 Napoli
The indigo molecule is imbedded into the channel. Water does not have access to the groove because the hydrophobic part of indigo repels it.
Nitric acid cannot attack the indigo double bond because of steric hindrance.
Quartieri - SILS 2006 Napoli
XAFS spectroscopy is a potentially very useful technique tobe applied in archaeological studies.
It is a non-destructive method which can be applied in air; itvirtually does not require any restriction on the type and size of the sample, which can be metal, ceramic, glass, cloth etc. and, finally, it is applicable to most of the elements of interest, even in very low concentration.
All these characteristics are particularly important in archaeological applications, in which samples are preciouscultural heritage made of very different materials.
Archaeometrical applications of X-ray Absorption Spectroscopy
Quartieri - SILS 2006 Napoli
Quartieri - SILS 2006 Napoli
The The originorigin of color in of color in ancientancient glassglass
Quartieri - SILS 2006 Napoli
Various colors in glass can be causedby metal ions in them.
They are usually transition elementswhich absorb characteristic frequencies
of visible region.
This mechanism is also influenced bythe oxidation state of the metal cation.
Quartieri - SILS 2006 Napoli
Since the characterization of colorant and decolorant componentsis important in understanding the
manufacturing technique, XAFS has been applied to the study of the oxidation state of transition metals
in a number of glass samplescharacterized by different color
Quartieri - SILS 2006 Napoli
Application of X-ray Absorption Spectroscopy with synchrotron radiation to the study of glasses of archaeological interest
(Quartieri et al. Eur. J. Mineral. 2002)
Synchrotron X-ray absorption spectroscopy has been applied to the study of the oxidation state of iron and manganese in a number of glass samples of the 2nd century AD, characterized by different color (from pale green to pale brown) found in the Roman villa of Patti, near Messina.
Quartieri - SILS 2006 Napoli
AIMS
-to test the influence of iron oxidation state on the color of the studied samples
- to identify the possible decolorant role of manganese oxide in the almost uncoloredsamples
Quartieri - SILS 2006 Napoli
The Fe and Mn K-edge XANES spectra were collected directlyon the glass fragments in the fluorescence mode on the GILDA-CRG beamline (ESRF).
A dynamically sagittally-focussing monochromator withSi(311) crystals and a 13-element high-purity Ge detector were used.
SiO2 TiO2 Al2O3 FeO MnO MgO CaO Na2O K2O NiO Cu2O CoO Cr2O3 ClA 70.70 0.10 3.31 0.40 0.02 0.63 8.02 16.45 0.59 0.02 0.06 0.02 — 0.99
B 65.89 0.18 3.39 1.00 1.20 1.11 8.98 14.31 1.15 0.06 0.03 — 0.02 0.91
C 65.51 0.20 2.83 0.97 1.40 1.24 8.72 17.45 0.69 — 0.06 0.02 0.01 0.88
ExperimentalChemical analyses of the glass samples.
Glass A: green; glass B: uncolored; glass C: pale brown.A
Quartieri - SILS 2006 Napoli
Fe K-edge
7100 7125 7150 7175
Nor
m. A
bsor
ptio
n
Energy (eV)
C
Olivine
Hematite
Magnetite
B
A
abcd
Quartieri - SILS 2006 Napoli
Glass A
7112.4 7113.9
7114.6
7110 7112 7114 7116 7118Energy (eV)
0
0.1
0.2
0.3
0.4
Nor
m. A
bsor
banc
e
Glass B
7112.3
7114
7110 7112 7114 7116 7118Energy (eV)
-0.5
0
0.5
1
1.5
2
Nor
m. A
bsor
banc
e
Glass C
7112.3
7114
7110 7112 7114 7116 7118Energy (eV)
0
0.2
0.4
0.6
0.8
1
Nor
m. A
bsor
banc
e
Olivine
7112.4
7113.6
7114.4
7110 7112 7114 7116 7118Energy (eV)
0
0.01
0.02
Nor
m. A
bsor
banc
e
Magnetite
7112.3
7114
7115.4
7110 7112 7114 7116 7118Energy (eV)
0
0.02
0.04
0.06
0.08
Nor
m. A
bsor
ptio
n
Hematite
7113.2
7114.5
7115.7
7110 7112 7114 7116 7118Energy (eV)
-0.005
0.005
0.015
0.025
0.035
Nor
m. A
bsor
ptio
n
Roman glass samples
Reference compounds
Fe K-edge:
Quartieri - SILS 2006 Napoli
6530 6540 6550 6560 6570
Nor
m. A
bsor
ptio
n
Energy (eV)
MnO
Glass B
Glass C
MnO2
Mn2O
3ab
c d
6540 6550 6560
Nor
m. A
bsor
ptio
n
Energy (eV)
Glass B
Glass C
Rhodonite
Tephroite
Mn K-edge
In glass B and C Mn is in the reduced form
Quartieri - SILS 2006 Napoli
In the ancient glass B and C Mn4+ has oxidized Fe2+ to Fe3+ and, as a consequence, is present in the reduced form.
This confirms the hypothesis of a redoxinteraction between iron and manganese, as a result of a deliberate addition of pyrolusite − reported in literature as one of the main decolorants in the Roman period − during the melting procedure of the almost uncoloredglasses.
Results
Quartieri - SILS 2006 Napoli
The glasswork of Val GargassaTHE ARCHAEOLOGICAL SITE
Quartieri et al. 2005
Quartieri - SILS 2006 Napoli
Quartieri - SILS 2006 Napoli
Production indicators: those remains which testify specific operationscarried out during the productive cycle (like melting, flashing, boiling, working) and which can be useful to reconstruct the technologicalprocesses and expedients used in the past to produce glass.
Glassartifact
cruciblesdrops
drippings
Vitreous massfragments
collarscuttings
Building materialsconcotti
THE ARCHAEOLOGICAL FINDINGS
Quartieri - SILS 2006 Napoli
worked glassdrippings
fluidity test
collars of blowing pipe
cuttings
Vitreous masses
Quartieri - SILS 2006 Napoli
US1-2
US1-3
US3-2
US5-1
US5-3
US5-1
US5-3
Glass artifacts
Fe K-edge
Sample Total area pre-edge Centroid (eV) Sample Total area pre-edge Centroid (eV)
US1-2 0.1356 7114.17 US5-3 0.1178 7113.26
US1-3 0.1838 7113.95 VGRH-US2-29 0.2080 7114.19
US3-2 0.1420 7113.52 VGRH-US2-27 0.1793 7114.23
US5-1 0.1465 7113.90 F-VGR34 0.1289 7113.36
ST1 0.1515 7113.68 ST2 0.1768 7113.70
Olivine 0.0521 7112.95 Hematite 0.0750 7114.56
Magnetite 0.2182 7114.06
Quartieri - SILS 2006 NapoliFeO = 0.4, MnO = 0.6
Addition of decolorant
FeO = 0.8, MnO = 0.0
F-VGR34
7112.7
7114.1
7114.7
7110 7112 7114 7116-0.01
0
0.01
0.02
0.03
0.04
0.05
-0.01
0
0.01
0.02
0.03
0.04
0.05
Pre-edge centroid7113.36 eV
VGRH-US2-27-
7112.8
7114.1
7114.6
7111 7113 7115 7117-0.05
0
0.05
0.1
0.15
-0.05
0
0.05
0.1
0.15
Pre-edge centroid7114.23 eV
St1
7111.8
7112.6
7114.1
7110 7112.3 7114.7 7117
0
0.02
0.04
0.06
0
0.02
0.04
0.06
Reference glass (Fe2+=40%)
Pre-edge centroid= 7113.68
US1-2
7112.5
7114.2
7115.4
7111 7113 7115 7117
0
0.02
0.04
0.06
0
0.02
0.04
0.06
US1-3
7112.7
7114.2
7115.2
7110 7112 7114 7116
0
0.02
0.04
0.06
0.08
0
0.02
0.04
0.06
0.08
US3-2
7111.9
7112.8
7114.2
7110 7112 7114 71160
0.01
0.02
0.03
0.04
0.05
0.06
0
0.01
0.02
0.03
0.04
0.05
0.06
US5-1
7112.7
7114.2
7115
7110.5 7112 7113.5 7115 7116.5
0
0.02
0.04
0.06
0.08
0
0.02
0.04
0.06
0.08
US5-3
7111.7
7112.6 7114.1
7114.7
7110 7112 7114 7116
0
0.01
0.02
0.03
0.04
0
0.01
0.02
0.03
0.04
St1
7111.8
7112.6
7114.1
7110 7112.3 7114.7 7117
0
0.02
0.04
0.06
0
0.02
0.04
0.06
Normalized Fe-K pre-edge spectra and the bestmodel for the glass artifacts
Quartieri - SILS 2006 Napoli
Quartieri - SILS 2006 Napoli
Luster decoration, typical of the Medieval and Renaissance pottery of the Mediterranean basin, consists of a metal-glass nanocomposite thin layer.
TEM measurements showed that luster consists of a thin film composed of a heterogenous distribution of silver and copper nanoparticles of sizes rangingfrom 5 to 100 nm.
These decorations show peculiar optical properties, producing brilliant reflections of different colors, cangiant effects and iridescences.
Quartieri - SILS 2006 Napoli
Quartieri - SILS 2006 Napoli
Red mosaic tesserae from Pompeii
(Arletti et al. APA 2006)
Red mosaic tesserae from Pompeii
(Arletti et al. APA 2006)1.5 mm 2 mm
Quartieri - SILS 2006 Napoli
Red mosaic tesserae from Pompeii(Arletti et al. APA 2006)
Red mosaic tesserae from Pompeii(Arletti et al. APA 2006)
-1
0
1
2
3
4
8950 9000 9050 9100
Cu K-Edge
Nor
m. A
bs. (
arbi
trar
y un
it)
Energy eV
CuO
Cu2O
Cu
Red Sample
0.5
1
1.5
2
2.5
3
Cu2O
C u
R ed Sam ple
8995.5
8994.5
8995.3
9011.1
9003.1
9003.0
Cu-XANES region
Quartieri - SILS 2006 Napoli
Red samples: Cu K-edgeRedRed samplessamples: Cu K: Cu K--edgeedge
0
0.5
1
1.5
2
0 1 2 3 4 5
FITEXP
R (Å1)
χ ׀(R
׀( (Å
-3)
a)
-1
-0,5
0
0,5
1
1,5
0 4 8 12 16
EXPFIT
Re
[ χ(q
)] (
Å-2
)
b)
k (Å-1) Cu - O Cu - Cu R (Å) N σ2(10-4 Å2) R (Å) N σ2(10-4 Å2)
Lipari 6 1.83±0.02 2.78±1.3 29±11 2.55±0.02 4.91±0.81 23±49 CuO 1.95±0.02 4 41±14 2.91±0.02 4 83±29 3.09±0.02 4 43±10 Cu2O 1.84±0.02 2 26±6 3.03±0.02 12 171±9 Cu met - - - 2.55±0.02 12 40±10
• Prevalent phase: Cu metallic clusters• Presence of Cu1+ in the glass matrix
• Absence of cuprite crystals
EXAFS region
ChalminChalmin etet al.al. APA (2006)APA (2006)
Quartieri - SILS 2006 Napoli
Quartieri - SILS 2006 Napoli
Quartieri - SILS 2006 Napoli
Quartieri - SILS 2006 Napoli
Natural deposit
A majority of charcoal pigment for horses
But also manganese oxide in two particular figures:
Non crystalline manganese oxide
?
?
Question of provenance
The case of The case of EkainEkain (Basque Country, Spain)
Upper Paleolithic (16500-12500 BP)
6520 6600 6680
Nor
mal
ized
abs
orba
nce
Energy (eV)
Point 1
Point 2
Groutite
deposit sampledeposit sample
Manganese localization
ESRF, ID21Point 1
Point 2
Head horse sample
GROUTITE
GROUTITEα-MnOOH
Mineral never identified before
The case of The case of EkainEkain (Basque Country, Spain)
Quartieri - SILS 2006 Napoli
Quartieri - SILS 2006 Napoli
Quartieri - SILS 2006 Napoli
CONCLUSIONS
- Various manganese oxides were identified as black prehistoricpigments, such as pyrolusite, romanechite, hollandite, cryptomelane, todorokite, manganite and groutite
- For the first time, manganite and groutite were identified aspigments. These minerals are very rare where the paintings wererealized unsuspected trade routes ?
- These Paleolithic people produced their own painting matter withoutapplying extensive heat treatments, but grounding together black pigments from different ores.