Source Analysis of Prehistoric Obsidian Artifacts in Sicily (Italy

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Chapter 11
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Publication Date (Web): October 15, 2013 | doi: 10.1021/bk-2013-1147.ch011
Source Analysis of Prehistoric Obsidian
Artifacts in Sicily (Italy) Using pXRF
Robert H. Tykot,*,1 Kyle P. Freund,2 and Andrea Vianello3
1Department
of Anthropology, University of South Florida,
Tampa, Florida 33620, U.S.A.
2Department of Anthropology, McMaster University,
Hamilton, Ontario, Canada LS8 4L8
3OUCS, Oxford University, England, Great Britain OX2 6NN
*E-mail: [email protected]
Obsidian artifacts have been found at many prehistoric sites
in Sicily, yet only a few studies have been done to determine
the specific geological sources and subsources used. In 2012,
nearly 600 artifacts from 25 archaeological sites dating from the
Neolithic, Copper, and Bronze Ages (ca. 6th-2nd millennia BC)
were analyzed non-destructively using a hand-held portable
X-ray fluorescence spectrometer, in museums that would not
allow removal of the artifacts. In addition, all of the artifacts
were techno-typologically analyzed to understand how obsidian
was reduced and used through time. A Bruker III-SD was used
to produce data for trace elements Rb, Sr, Y, Zr, and Nb which
were calibrated against international obsidian standards, and
compared with results obtained with the same instrument on
geological sources and subsources in the Mediterranean region.
All artifacts tested came either from Lipari or Pantelleria,
confirming visually-based predictions but also demonstrating
that multiple geological subsources were used on each island.
The majority of the obsidian artifacts were blades, while a small
percentage were cores. These results are used to assess variation
based on site location, time period, and lithic typology, and to
inform us about contact, exchange, and socioeconomic aspects
of the ancient societies involved and if they changed over time.
© 2013 American Chemical Society
In Archaeological Chemistry VIII; Armitage, R., et al.;
ACS Symposium Series; American Chemical Society: Washington, DC, 2013.
Obsidian in Sicily
Extensive studies of obsidian sources, and archaeological sites in mainland
Italy, Sardinia, and Corsica have been done over the past 20 years, but few
chemical analyses (1–6) have been done in Sicily despite its large contribution
to archaeological lithic assemblages (Figure 1). The proximity of the island
sources of Lipari and Pantelleria to Sicily makes them the most likely used during
the Neolithic period, but the realization that different geological subsources on
each may have been utilized requires more than visually-based identification (7).
Chemical analysis would also indicate whether any obsidian from Palmarola,
Sardinia (Mt. Arci), or elsewhere made its way to Sicily.
Obsidian Sources
Lipari, one of the Aeolian Islands just north of Sicily, is well known for its
high-quality obsidian, black or gray but often highly transparent, and frequently
with phenocrysts (Figure 2). Detailed recording, collection, and elemental analysis
of source material has revealed two geological subsources near the coast in the
northeastern part of Lipari – Gabellotto Gorge and Cannetto Dentro – that had
produced obsidian usable for stone tools in prehistoric times (8). While Gabellotto
has a large number of visible outcrops, Cannetto Dentro is restricted to a very small
area, and access and quantity may have been somewhat different prior to historic
lava flows which include Forgia Vecchia and Rocche Rosse. Artifacts made of
Lipari obsidian have been found throughout peninsular Italy, as far as southern
France and the Istrian peninsula of Croatia, and in Malta and Sicily (9). Prior to
this study, all obsidian artifacts assigned to Lipari were specifically matched to
Gabellotto.
Pantelleria, southwest of Sicily, is known for its greenish peralkaline
obsidian, while chemical analyses can distinguish between subsources near Lago
di Venere in the north, and the three volcanic events at Balata dei Turchi near the
south coast (10) (Figure 3). Artifacts of Pantellerian obsidian have been found
at archaeological sites as far as northern Italy, but mainly in Tunisia, Malta, and
southern-western Sicily. In most cases, multiple Pantelleria subsources were
being utilized, despite the small quantity and size of the Lago di Venere material.
196
Figure 1. The four Italian island obsidian sources (in all caps), and
archaeological sites with 10 or more scientific analyses (sites in bold analyzed by
Tykot; in italics by other scholars and Tykot; in plain text by other scholars).
197
Figure 2. A geological map of Lipari showing multiple volcanic lava flows.
Gabellotto Gorge and Canneto Dentro obsidian lava flows date to cycle IX.
198
Figure 3. A geological map of Pantelleria showing multiple obsidian outcrops
and surface finds.
Obsidian Artifacts Tested in Sicily
In 2012, technological and elemental analyses of obsidian artifacts were
done in the Paolo Orsi Archaeological Museum in Siracusa and the Antiquarium
“Arturo Petix” in Milena. The obsidian assemblages include blades, cores, and
scrapers (Figure 4), and come from 26 sites (Figure 5). The artifacts from some of
these sites were not excavated but collected on the surface, while other sites were
excavated long ago, with most just assigned to general chronological periods.
While the earliest sites tested date to the Middle Neolithic (ca. 5th millennium
cal BC), obsidian from Lipari and Pantelleria is known to have been used in the
Early Neolithic (6th millennium cal BC), e.g. at Grotta dell’Uzzo (2). A summary
of our data for nearly 600 obsidian artifacts (individual artifact data available on
request)is provided in Table I.
199
Figure 4. Prehistoric obsidian artifacts from Sicily. Blades and bladelets (left);
scraper (upper right); core and other tools (lower right). Courtesy of R.Tykot.
Figure 5. Map showing sites tested in this study (listed in Table I). Dots in yellow
represent sites where 10 or more artifacts have been tested before. Sites 17-20,
25-26 also had been analyzed by La Rosa et al. (2).
200
Elemental Analysis
A portable XRF instrument was used in this study because it is
non-destructive, analyses could be performed within the museums and thus
without special permissions for export out of Italy, and rapid analysis of
statistically robust datasets. A Bruker III-SD was equipped with a filter (12 mm
Al, 1 mm Ti, 6 mm Cu) designed to enhance data measurements of mid-Z elements
in the spectrum, while settings of 40 kV and 11 μA were selected to maximize
trace element analysis. Analyses were done on cleaned obsidian artifacts for
120 seconds. Prior studies by the first author had been done with a Bruker III-V
and run for 180 seconds, while this instrument has a silicon-drift detector which
is faster and allows for more rapid analyses. The Bruker III-SD also was used
to re-analyze many geological samples from all of the European/Mediterranean
island sources, showing that each could be discriminated, along with subsources
for each (Carpathian, Lipari, Melos, Palmarola, Pantelleria, Sardinia). The
resulting data for rubidium (Rb), strontium (Sr), yttrium (Y), zirconium (Zr), and
niobium (Nb) were calibrated into ppm values using obsidian standards shared
between many laboratories, and compared with the geological database. There
was only a small offset in the numeric values produced relative to the previous
model. The geological obsidian sources for each island (and Carpathia) are easily
discriminated using just a few trace elements, especially as ratios (Figure 6).
Nevertheless, for attribution to island sources and specific subsources, results for
all elements are examined and evaluated. The four main Sardinian (Mt. Arci)
subsources may also be discriminated using Rb, Sr, and Nb, and even subdivided
further based on specific geological outcrop locations (11). Fe and Rb show
significant differences in the Lipari subsource localities (Figure 7), while Zr and
Nb separate the Lago di Venere and Balata dei Turchi subsources on Pantelleria
(Figure 8).
201
202
Table I. Summary data for each site tested. The location of each site is provided in Figure 5.
Gabellotto
Gorge
Cannetto
Dentro
Balata dei
Turchi
Lago di
Venere
Obsidian
Samples
Cores
Blades
Flakes
Angular
Waste
Middle
Neolithic
131
2
0
0
133
3
55
67
8
Tre Fontane
Middle
Neolithic
61
1
0
0
62
1
54
7
0
8
Megara Hyblaea
Middle
Neolithic
10
0
0
0
10
1
9
0
0
7
Matrensa
Middle
Neolithic
124
0
0
0
124
2
71
46
5
21
Fontana di Pepe
Middle
Neolithic
4
0
0
0
4
0
2
2
0
Serra del Palco
MiddleLate
Neolithic
32
0
8
2
42
0
23
19
0
Rocca Aquilia
MiddleLate
Neolithic
3
0
0
0
3
0
3
0
0
25
Iannicu
MiddleLate
Neolithic
3
0
0
0
3
0
3
0
0
17
Fontanazza
Monte Grande
Grotta 4
MiddleLate
Neolithic
28
2
2
4
36
0
19
17
0
No.
Site
Dating
14
Stentinello
15
18
19
203
Gabellotto
Gorge
Cannetto
Dentro
Balata dei
Turchi
Lago di
Venere
Obsidian
Samples
Cores
Blades
Flakes
Angular
Waste
MiddleLate
Neolithic
12
0
2
0
14
1
11
2
0
Fontanazza
Monte Grande
Grotta 2
MiddleLate
Neolithic
1
0
0
0
1
1
0
0
0
20
Mizzebbi
MiddleLate
Neolithic
5
0
0
0
5
0
3
2
0
10
Palazzola
Acreide
Neolithic
4
0
0
0
4
0
4
0
0
6
Grotta Corruggi
Neolithic
2
0
0
0
2
0
2
0
0
Poggio Rosso
Neolithic
to Copper
Age
22
0
0
0
22
0
22
0
0
Sant’Ippolito
Neolithic
to Copper
Age
5
0
0
0
7
2
5
0
0
Calaforno
Neolithic
to Copper
Age
9
0
0
0
9
1
3
5
0
No.
Site
Dating
17
Fontanazza
Monte Grande
Sommita
17
11
12
1
Continued on next page.
Site
Dating
Gabellotto
Gorge
Cannetto
Dentro
Balata dei
Turchi
Lago di
Venere
Obsidian
Samples
Cores
Blades
Flakes
Angular
Waste
22
Grotta del Conzo
Early
Copper
Age
1
0
0
0
1
0
1
0
0
24
Contrada Orto del
Conte
Early
Copper
Age
70
0
0
0
70
0
67
3
0
Grotta Calafarina
Early
Copper
Age
9
0
0
0
9
0
9
0
0
Menta
Middle
Copper
Age
1
0
2
0
3
0
1
2
0
23
Malpasso
Late
Copper
Age
4
0
0
0
4
0
4
0
0
13
Serraferlicchio
Copper
Age
4
2
0
0
6
0
5
1
0
Castelluccio
Early
Bronze
Age
1
0
0
0
1
0
0
1
0
Monte Sallia
Early
Bronze
Age
1
0
0
0
1
0
0
1
0
No.
5
204
Table I. (Continued). Summary data for each site tested. The location of each site is provided in Figure 5.
26
2
9
Site
Dating
Gabellotto
Gorge
Cannetto
Dentro
Balata dei
Turchi
Lago di
Venere
Obsidian
Samples
Cores
Blades
Flakes
Angular
Waste
16
Gela Manfria
Early
Bronze
Age
1
0
0
0
1
0
0
0
1
4
Cozzo del
Pantano
Early
Bronze
Age
1
0
0
0
1
0
1
0
0
3
Cava
Canabarbara
Early
Bronze
Age
10
0
0
0
10
0
8
0
2
Total
559
7
14
6
588
12
385
175
16
Percent
95.1
1.2
2.4
1.0
100
2.0
65.5
29.8
2.7
205
No.
Figure 6. Distinguishing the European/Mediterranean obsidian sources, and
Monte Arci (Sardinia) subsources, using geological samples. The ellipses
encompass all of the geological samples tested.
Results and Discussion
For the 588 obsidian artifacts analyzed, 96.6% match with Lipari, and just
3.4% with Pantelleria. For no artifact was the source not clearly distinguished
from others in the Mediterranean area. The artifacts include 57 at the Antiquarium
in Milena which had been analyzed previously by La Rosa et al. (4) using a
non-commercial, portable XRF, with the reanalysis adding the identification
of the specific subsources used at those sites (17-20, 25-26 in Figure 5). The
dominance of Lipari obsidian is not a surprise, considering the proximity of the
Aeolian Islands to Sicily, and the extensive distribution of Lipari obsidian both
to the north (peninsular Italy, Croatia) and south (Sicily, Malta). Obsidian from
Cannetto Dentro, however, was identified at several of the sites tested in this
study, while previous pXRF analyses for many sites in mainland Italy, Croatia,
and Malta were all assigned to Gabellotto Gorge (Figure 7). This has significant
implications for our understanding of access and distribution of obsidian from
Lipari in the Neolithic and Copper Ages.
206
Figure 7. Artifacts assigned to two Lipari subsources represented by ellipses,
with 560 assigned to Gabellotto Gorge and 8 to Canneto Dentro.
Figure 8. Artifacts assigned to two Pantelleria subsources, as represented by
ellipses, with 14 assigned to Balata dei Turchi and 6 to Lago di Venere.
207
Only three of the twenty-six sites tested have artifacts from Pantelleria, with
all three located in central-western Sicily. All but two of the fourteen Pantelleria
artifacts come from Middle or Late Neolithic sites. While none were present at
six other sites in this area, including two near the southern coast, the number of
artifacts found and tested at these sites was very small. For the sites in western
Sicily, all those with a significant number of artifacts tested include some from
Pantelleria.The absence of Pantelleria obsidian at the sites tested in eastern Sicily
supports the visual assessments published by Nicoletti (7), and overall is not
surprising given the greater distance from the source.
The modest quantity of Pantelleria obsidian making its way to Sicily also is
not surprising considering the substantial open-water distance that needed to be
crossed, and the limited population living on the small island in the Neolithic
(as inferred from field surveys and sporadic finds, e.g. in contrada Buggeber)
(12). Assigning a fairly large percentage (30%) of the Pantelleria obsidian artifacts
to Lago di Venere, which is located inland and for which the quantity and size
of the raw material is rather limited, supports a preliminary interpretation that
obsidian was irregularly brought to Sicily, after collection and reduction by local
residents, rather than visitors from Sicily accessing directly obsidian from the
extensive coastal Balata dei Turchi subsources. Nevertheless, more information
about the reduction and use of these subsources is needed before more concrete
interpretations can be made.
For the artifacts assigned to Pantelleria, five of six from the Lago di Venere
subsource were blades while one artifact was a flake. Ten of the seventeen artifacts
from Balata dei Turchi were blades and the rest were flakes. The percentages
of blades and flakes are quite similar to those from Gabellotto Gorge (n=559;
65% blades, 30% flakes). Canneto Dentro obsidians included three flakes and
four blades. Overall, all cores tested (n=12; 2% of total artifacts) came from the
Gabellotto subsource.
Despite differences in the procurement of the various raw materials, obsidian
from both Lipari and Pantelleria were reduced in a similar manner. Our results
clearly show that blades were the primary obsidian artifact type found in Sicily
from the Neolithic through Bronze Ages. This long tradition of blade production
differs from other regions in the western Mediterranean, such as Sardinia, where
obsidian was used for a greater variety of tool types (13), and where post-Neolithic
reduction strategies were more oriented towards the production of expediently
produced flake tools (14). The continued usage of obsidian in central and eastern
Sicily during the Chalcolithic and Bronze Ages contrasts with elsewhere in the
larger western Mediterranean, where obsidian use declined at the end of the
Neolithic (ca. 3000 BC).
Conclusion
The use of pXRF is clearly successful in distinguishing not only between
the different Mediterranean island sources, but also the important subsources
on Lipari and Pantelleria. The ability to rapidly analyze obsidian artifacts
non-destructively and within museums was what allowed this research to be done,
208
and obsidian from many more sites in central and western Sicily, and Calabria, will
be tested in the future. This will enable a much greater statistical understanding
of the direction and socioeconomic circumstances of obsidian production and
distribution in the south-central Mediterranean during the Neolithic through Early
Bronze Age periods, and when combined with archaeological evidence for flint
and other stone tools, ceramics, and other materials, hypotheses may also be
tested regarding chronological change. Direct comparisons may also be made
with the more extensive data available for the north-central Mediterranean region.
Acknowledgments
This research would not have been possible without the openness of the
director of the Paolo Orsi museum in Siracusa, Dr. Beatrice Basile and the
invaluable help of Dr. Anita Crispino, and all technical staff at the museum. We
are particularly grateful to Mr. Michele Uccello for his assistance during our time
at the museum. We thank also the superintendent of Caltanissetta, Dr. Salvatore
Gueli, and Dr. Carla Guzzone of the same superintendency for granting us access
to the Antiquarium in Milena and to Mr. G. Palumbo for assisting us on site.
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210

Source Analysis of Prehistoric Obsidian Artifacts in Sicily (Italy

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