Using Portable XRF for Elemental Analysis of Obsidian

Using Portable XRF for Elemental Analysis of Obsidian, Metals,
Ceramics, and Other Archaeological Materials
Robert H. Tykot, University of South Florida
email: rtykot@cas.usf.edu
Corsica
Palmarola
Monte Arci
Sardinia
Lipari
Antiparos
Pantelleria
Mediterranean Sources, and
Archaeological Sites
with Obsidian Artifacts
(Sardinian, Aegean,
Carpathian sites not shown)
Melos
Gia
Typical neolithic obsidian tools
Most sites also have flakes and tools less formal
Monte Arci (Sardinia) Obsidian
Obsidian from
Primary Deposits at
Conca Cannas (SA)
easily collectible
Four main subsource groups:
SA, SB1, SB2, SC
with further subgroups identifiable
SB1a, SB1b, SB1c, SC1, SC2
Visual and Physical Differences
Density
Measurements
Useful
Lipari
Palmarola
Pantelleria
Sardinia A
Sardinia B1
Sardinia B2
Sardinia C
2.3
2.35
2.4
2.45
Density
2.5
2.55
Electron Microprobe
Major and minor elements only
1-inch disks with 14-16 samples
Electron Microprobe Discrimination of Monte Arci Subsources
14.5
Al2O3 (%)
14
SA
SB1
SB2
SC
13.5
13
12.5
5
5.5
K 2O (%)
6
multivariate statistical analysis provides even clearer distinctions
Obsidian from Filiestru Cave (Sardinia) over 4 Neolithic Periods
%
27
20
29
10
100
80
SC
SB2
SB1
SA
60
40
20
0
Cardiale
Filiestru
Bonu Ighinu
Ozieri
published in Journal of Mediterranean Archaeology (1996)
Missouri University Research Reactor
Instrumental Neutron Activation Analysis (INAA)
Laser Ablation ICP-Mass Spectrometry
(with Michael Glascock & Jeff Speakman)
Laser ablation
sample holder
and instrument
Laser ablation trace
200 wide
Laser Ablation Inductively
Coupled Plasma Mass
Spectrometer (LA-ICP-MS)
at U Missouri
microscopic signature left
X-Ray Fluorescence Spectrometer
non-destructive, if sample
fits in the sample holder
modern XRF instrument: needs liquid nitrogen to
maintain vacuum and analyze lower Z elements
automated sample system
X-Ray Fluorescence
An electron in the K shell is ejected
from the atom by an external primary
excitation x-ray, creating a vacancy
An electron from the L or M
shell "jumps in" to fill the
vacancy, and emits a
characteristic x-ray unique
to this element
When a vacancy is created in the L shell, an electron from
the M or N shell "jumps in" to occupy the vacancy. In this
process, it emits a characteristic x-ray unique to this element
Multiple X-rays are produced, with characteristic energies,
for each element in the sample
Overlaps are minimized by using filters, and different beam
settings (voltage and current)
Portable XRF Systems
ElvaX
Bruker, with vacuum
Niton
Bruker, on tripod
Portable X-Ray Fluorescence Spectrometer (pXRF)
Advantages
 Non-destructive
 Any size sample
 Quantitative analysis
 Low Z elements (w/ vacuum)
Settings for pottery analysis
 no filter
 40 kV, 1.5 μA, 180 seconds
 results calibrated against standards
Isolino di Varese
Zagreb area
Les Terres Blanches
Gaione
Combes
Arene
Candide
San Polo
Fornace Cappuccini
Istria sites
Pokrovnic
Grotta all’Onda
Giribaldi
Danilo
Casa Querciolaia
La Cabre
Lumaca
Paduletto di Castagneto
Pietracorbara
Strette
Colle Cera
Susac
A Petra
Pianosa Orbetello Catignano
Monte Ortu, A Fuata, Carcu
Monte Grosso
Poggio Olivastro
Sarra Cinescu
Giglio
Monte Lazzu Castellare
La Marmotta
St. Pancrace-Tiggianese
I Calanchi
Santo Stefano
Cardiccia
Casale del Dolce
Basi
Tavoliere
Passo di Corvo
Liscia Pilastru
Monte d'Accoddi
Contraguda
Pulo di Molfetta
Grotta Sa Corona
Palmarola
Grotta Filiestru
Sa Ucca de su Tintirriolu
Molia
Duos Nuraghes
S. Caterina di Pittinurri
Mt.
Arci
Cuccuru s'Arriu
Ortu Comidu
Domu Beccia
San Gemiliano
Serra Cannigas
Buon Cammino
Cuccuru Craboni
Cuccuru Ibba
Barbusi
Su Carroppu
Antigori
Acconia
Is Solinas Tracasi
Ustica
Lipari
Grotta dell'Uzzo
Ste. Catherine
Bova Marina
Zembra
Mursia
5 sites
Pantelleria
Hergla
250 Km
Brochtorff
Skorba
Tas-Silg
Obsidian analyses by:
• Acquafredda & Muntoni, in press
• Ammerman et al. 1990
• Ammerman & Polglase 1997
• Barca et al., in press
• Berton et al. 2004
• Crisci et al. 1994
• Crummett & Warren 1985
• de Francesco & Crisci 2000
• Francaviglia & Piperno 1987
• Lugliè et al. 2007a; 2007b
• Mello 1983
• Michels et al. 1984
• Pessina & Radi 2006
• Petrassi & Zarattini 1997
• Tykot 1995…2009
Monte Arci Subsource Distribution
Early Neolithic Sites in Sardinia and Corsica
%
100
21
10
10
42
26
20
27
35
96
80
Sardinia C
Sardinia B
Sardinia A
60
40
20
Su Carroppu
Santa Caterina
Filiestru - Filiestru
Filiestru - EN
Sa Corona - Filiestru
A Petra
Strette
Pietracorbara
Lumaca
0
Monte Arci Subsource Distribution
Late Neolithic Sites in Sardinia & Corsica
%
100
10
181
93
11
62
17
83
22
29
24
11
10
80
Sardinia C
Sardinia B
Sardinia A
60
40
20
59
20
17
21
5
80
Sardinia C
Sardinia B
Sardinia A
60
40
20
Monte Lazzu
Castellari
A Fuata
Lumaca
I Calanchi
Basi
Saint Pancrace
Monte Grosso
Strette
0
Tracasi
Barbusi
Is Solinas
Cuccuru Ibba
125
S. Gemiliano
10
Molia
20
Sa Ucca
Monte d'Accoddi
12
Filiestru
Contraguda
100
Li Muri
%
Liscia Pilastru
0
Open-air, Late Neolithic
site of Contraguda
Areas excavated at Contraguda (above);
Structural feature A-B (left)
Contraguda Results (246 analyses)
%
100
%
47
152
9
28
10
100
90
45
22
81
5
90
80
SC
SB2
SA
70
60
80
70
60
50
50
40
40
30
30
20
20
10
10
0
SC
SB2
SA
0
unlisted
Area 3
Area 4
Area 19
Area 20
Comparison of subsources present in
different areas of the Contraguda site
(combined LA-ICP-MS and pXRF
data)
Area 3
Area 3 Str. A
Area 3 Str. B
Area 3 Tumulo B
Comparison of subsources present
within Area 3 at Contraguda
(combined LA-ICP-MS and pXRF
data)
Sardinia (Italy)
Contraguda
Previous analytical studies mostly
in northern (e.g. Filiestru Cave)
Grotta Filiestru
Obsidian from 15 sites in the Museo
Pigorini collections tested here, plus
from open-air site of Contraguda
Frumini
Serra de Castius
Is Arrius
Palas de Casteddu
Mes’e Arrius
Nghe. Nieddu
La Gumarense
Palmas Arborea
Triarzu
Nghe. Loddu
Su Casteddu Becciu
Simaxis
Nghe. Tiria
Monte Arci
Pigorini Collection
S. Bartolomeo & S. Elia cave artifacts acquired in
1880s by Francesco Orsoni; Oristano area surface finds
collected in 1899 by T. Zanardelli
San Bartolomeo
Sant’Elia
Examples of Obsidian Artifacts Tested from Museo Pigorini
Note some visual differences in transparency, luster, inclusions
Archaeological Sites in Sardinia from Pigorini Museum collection
SiteTime
Su Cuccuru de Is Arrius (Cabras)
Grotta San Bartolomeo (Cagliari)
Grotta Sant'Elia (Cagliari)
Simaxis
Palas de Casteddu (Cabras)
Mes'e Arrius (Cabras)
Stazione La Gumarense (Santa Giusta)
Domus de janas di Triarzu (Paulilatino)
Cantoniera Frumini (Sili)
Palmas Arborea (Oristano)
Serra de Castius (Sili)
Su Casteddu Becciu (Fordongianus)
Nuraghe Tiria (Villaurbana)
Nuraghe Loddu (Fordongianus)
Nuraghe Nieddu (Oristano)
Middle Neolithic
Late Neolithic
Neolithic?
Neolithic
Late Neolithic
Late Neolithic
Late Neolithic-Chalcolithic
Neolithic-EBA
Chalcolithic
Chalcolithic
Chalcolithic
Chalcolithic-EBA?
Nuragic
Nuragic
Nuragic
total
VisualpXRF
13420
15440
2110
1010
1010
5910
99
1010
1010
44
1010
88
1010
98
109
468178
Using Rb, Sr, Y, Zr, Nb to
identify obsidian sources
High Rb relative to low Sr
Roughly equal Rb and Sr
pXRF Discrimination of Monte Arci Subsources
and Assignment of Artifacts
SC
SB
SA
multivariate statistical analysis provides even clearer distinctions
Map of Sardinia
shows obsidian source area (Monte
Arci) and the area of Nuragic sites
with obsidian tested
Central Marghine Region in Sardinia
large cluster of Nuragic sites occupies about 40 sq km in Borore and adjacent comuni
Nuraghi in the Marghine Area
Excavations near Tower A at Duos Nuraghes
In the mid-1980s led by Penn State faculty Joseph Michels & Gary Webster
Excavations done first in the village area outside of the nuraghi…
A
B
…followed by excavations within the nuraghi
Distinctions visibly clearer using multiple elements
13
SA
SB1
SB2
SC
Rb/Nb
10
7
4
1
0
3
6
Sr/Nb
9
Nearly 300 artifacts tested for these 5 Marghine sites
%
100
228
71
80
SA
SB1
SB2
SC
60
40
20
Other Sites
Duos Nuraghes
0
Only about 90 artifacts
tested in total for six other
Nuragic sites
Over 200 tested from specific contexts within Duos Nuraghes
%
100
39
15
168
SA
SB1
SB2
SC
80
60
40
20
Village
Nuraghe B
Nuraghe A
0
145
Antiguri
10
Ortu Comidu
71
Domu Beccia
228
Marghine
9
Duos Nuraghes
8
Nieddu
10
Loddu
100
Tiri
Other Nuragic Sites Tested
%
13
80
60
SA
SB
SC
40
20
0
The Chaîne Opératoire
Reduction
Modification
Production
Use
Re-use
Deposition
Acquisition
(extraction)
Transport
Exchange
Greenstone and Copper Artifacts from Florida tested
Pure copper, consistent with native (natural)
copper, rather than smelted from copper ore.
From the Blueberry Site
Soil Samples
Use in lab, field, museums…
…on stone, metals, ceramics, etc.
Orlando Museum of Art – South American Collections
More Examples of Testing at the Orlando Museum of Art
Tampa Museum of Art – Classical Period Metal Artifacts
More Examples of Metal Artifacts Tested at Tampa Museum of Art
Silver object in Tampa Museum of Art
Brass object in Tampa Museum of Art
Malta National Museum of Archaeology, Valletta
tested obsidian from residential site of Skorba
and mortuary complex of Brochtorff Circle
Malta National Museum of Archaeology, Valletta
Tested wooden sculpture to see if
there was gold paint on surface...
Tested statue to see if modern
or ancient gold alloy...
...and it appears to be truly ancient
...and there was!
Analysis of Copper-Based Artifacts from Morocco, at University of Siena, Italy
Specifically testing to see whether objects were
brass (containing zinc), rather than pure copper
or bronze (containing tin)
At USF - testing human bone samples to look at diet
(differences between terrestrial plants/animals and seafood)
need to use vacuum to detect phosphorus (P) –
important for comparison with calcium (Ca),
strontium (Sr), and barium (Ba) values
Human bone sample from coastal site of Is Arrutas, Sardinia
note Sr peak
Human bone sample from inland site of Scab'e Arriu, Sardinia
note lower Sr peak
remember, this is just the visual concentration peaks; calibrated numeric values are what is significant
Yon Mound (Apalachicola, Florida)
excavations by Nancy White & Jeff DuVernay (USF)
Fort Walton Incised
Lamar Ceramic Types
For homogeneity, powder samples removed by drilling...
...while analyses of clean surfaces also shown to be consistent and reliable
pXRF of Yon Mound Ceramics
Florida Ceramics
(tested samples for Tom Pluckhahn)
Differences in ceramic
composition for Sr, Zr
pXRF of inner surface of Yon Mound ceramics (2009)
1.6
CheckStamped
1.4
Fort WaltonIncised
Zr/Sr
LakeJacksonIncise
1.2
LakeJacksonPlain
Lamar ComplicatedS
1
MarshIslandIncise
SandTemperedPlain
0.8
0.6
0.9
1
1.1
1.2
1.3
1.4
1.5
Rb/Sr
note cluster of Lamar Complicated Ware samples, while probably multiple
sources of Fort Walton and Marsh Island incised wares
Kolomoki (Georgia)
(excavations by Tom Pluckhahn)
Ceramic Samples from Kolomoki (Georgia)
180
13
170
93
Zirconium (ppm)
160
150
24
140
8
130
120
31
5
238
46
29
110
203
100
83
90
80
100
110
120
130
140
150
Strontium (ppm)
note: one or two central groups (local?), plus several outliers (from other sources?)
Poverty Point & St. Johns Pottery from Florida and Louisiana
2
C h e c k S ta m p e d
F o r t W a lto n I n c is e d
L a k e J a c k s o n I n c is e d
L a k e J a c k s o n P la in
L a m a r C o m p lic a te d S ta m p e d
M a r s h I s la n d I n c is e d
S a n d T e m p e r e d P la in
C la ib o r n e - P P O
C la ib o r n e - S t. J o h n s
P o v e r ty P o in t - P P O
P o v e r ty P o in t - S t. J o h n s
A p a la c h ic o la - P P O
T ic k I s la n d - P P O
T ic k I s la n d - S t. J o h n s
T ic k I s la n d - W a lle r
Zr/Sr
1 .5
1
0 .5
0
0
0 .5
1
R b /S r
1 .5
Many possible applications, but need to ...
... have specific purpose for the testing;
... know what elements should be tested;
... have other data to compare with
... remember that analysis is of surface (if sample not powdered)
Florida possibilities include:
... sourcing ceramics;
... sourcing recently found obsidian;
... identifying native vs. historic metals;
... composition of metal alloys (ancient and modern tools, jewelry);
... soil testing (ancient activities, modern contamination);
... seafood consumption (by testing bones)
Samples can be solid, powder, or liquid
Portable and precise...
but not inexpensive!
And does require use by
someone trained in Xray analysis and data
processing
Thank you!
If interested in collaborative research projects, I can be contacted at:
813 974-7279 (office phone)
rtykot@cas.usf.edu (email)
http://shell.cas.usf.edu/~rtykot (website)
or just google “Tykot”