fibula and snake bracelet from albania. a case study by om, sem

SCIENTIFIC CULTURE, Vol. 2, No. 2, (2016), pp. 9-18
Copyright © 2016 SC
Open Access. Printed in Greece. All Rights Reserved.
DOI: 10.5281/zenodo.44895
FIBULA AND SNAKE BRACELET FROM ALBANIA.
A CASE STUDY BY OM, SEM-EDS AND XRF.
Olta Çakaj1, Teuta Dilo1, Gert Schmidt2, Nikolla Civici3, Frederik Stamati4
1Faculty
2Institut
of Natural Science, University of Tirana, Albania
für Keramik, Glas- und Baustofftechnik, TU Bergakademie Freiberg, Germany
3Centre of Applied Nuclear Physics, Albania
4Centre of Albanological Studies, Tirana, Albania
Received: 20/11/2015
Accepted: 17/01/2016
Corresponding author: Olta Çakaj ([email protected])
ABSTRACT
Albania is situated west of the Balkan Peninsula while Shkodra and Durrës are respectively north-western
and western cities. The objects of this study are a fibula (IX-VIII BC) found in Shkodra and a snake bracelet
(III-I BC) found in Durrës. The purposes of this research paper are to study the chemical composition, production technology, corrosion products, microstructure and the possible minerals used for the objects’ manufacture. To fulfil these tasks the objects’ samples have been analysed with μ-XRF, OM, Vickers microhardness tester and SEM-EDS. Both objects resulted authentic copper-tin alloys with less than 2% of lead. They
have approximate microhardness values (116.2HV and 113.6HV), with corrosion products from the first and
second oxidized layer. The fibula and the snake bracelet has been casted, hot and cold worked to obtain the
final shape. Both objects have lead and copper-iron-sulphur inclusions which suggest the possible use of
copper-iron sulphite minerals.
KEYWORDS: antique bronze, microstructure, texture, OM, SEM-EDS, μ-XRF
10
Olta Çakaj et al
1. INTRODUCTION
This research was performed in order to study
the alloy composition of two antique objects, their
distinct production technology and the possible
mineral used as raw material. This was archived
through the examination of the samples’ chemical
content, their microhardness, microstructure and its
inclusions or secondary phases. Another section of
the article covers the qualitative determination of the
corrosion products which is essential to prove the
objects’ authenticity (not fake replicas) and is helpful
for the conservation process.
Albania has a favourable link position between
Europe and Asia. Scodra (in Latin, today Shkodra)
on the northwest of Albania was the capital of Ardiaei kingdom since the III century BC. While Dyrrachium (in Latin, today Durrës) was founded during
the XIII - XI century BC and became one of the most
important port cities of the western Balkan Peninsula
(figure 1a). After the XI century BC the first iron objects began to appear marking the initiation of the
Iron Age but it took almost three centuries for this
new chemical element to substitute partially bronze
in working tools and weapons. During this time
copper alloys were more preferable in the production of ornaments and jewellery. Later on the Hellenistic Period was associated with the spread of Greek
culture influences and trade exchanges during the
expansion of the Empire founded by Alexander the
Great. (Prendi 1977-1978; Boardman et al. 1982;
Jacques 1995; Ceka 2000)
Most of the copper deposits from the Jurassic and
Cretaceous periods are present in the volcanogenic
massive sulphide compositions. They are located in
Albania, Cyprus and a few in Turkey (Kure Asikoy,
Murgul Maden, etc.) but are very rare in other countries. (Economou-Eliopoulos et al. 2008; Hoxha 2014)
Many chemical mineralogical studies have been performed through the years for the Albanian territories. The central north (Rubik) and north (Mirditë)
underground resulted rich in copper-sulphide minerals associated with zinc such as pyrite (FeS2) - chalcopyrite (CuFeS2) - sphalerite [(Zn,Fe)S]. Later on
because of the hydrothermal solutions changes and
the partial oxygen pressure increments the quantity
of chalcopyrite mineral had decreased and bornite
(Cu5FeS4) had taken its place (figure 1b). (Çina 1975,
1976; Koçi 1977; Kati 1988) Two ancient and important mines in the region are Rudna Glava of Serbia and Ai Bunar of Bulgaria. According to different
studies their copper mineral deposits are hydro carbonate such as azurite (Cu3(CO3)2(OH)2) and malachite (Cu2CO3(OH)2). (Jovanovic 1978; Gale 1990)
The copper sources were so many and so important
in Cyprus since early times that its name derives
from this chemical element. The copper ores of Cyprus are hydro carbonate and sulphate such as malachite (Cu2CO3(OH)2), azurite (Cu3(CO3)2(OH)2) and
chalcopyrite CuFeS2. (Constantinou 1982) While in
Greece the regions rich in copper ores where is
thought that objects production was supported by
local copper deposits are Kamariza, Ilarion, Christiana, Agia Varvara, Sounion and Lavrion. According
to the literature copper was obtained from native
copper (Cu), cuprite (Cu2O), chalcopyrite (CuFeS2),
malachite (Cu2CO3(OH)2), azurite (Cu3(CO3)2(OH)2),
chalcocite (Cu2S), covellite (CuS), olivenite
(Cu2AsO4OH), atacamite (Cu2Cl(OH)3) and tetrahedrite ((Cu,Fe)12Sb4S13) (figure 1a). (Marinos & Petrascheck 1956)
Few studies have been performed about Albanian
copper based objects this last years while other Balkanic countries have studied nearly all their culture
heritage with physical and chemical analytical
methods. Although Albania has a rich museum fund
only a few objects have been studied so far. 122 silver alloy coins from a hoard (III B.C.), minted by the
Illyrian king Monounios and the ancient cities of
Dyrrachium (Durrës) and Korkyra (Korfuz) was
studied with EDXRF. One coin from Dyrrachium
(Durrës) and one of Illyrian king Monounios from
the III century B.C. resulted copper-silver alloys
produced with a cold-struck process after casting.
(Pistofidis et al., 2006; Civici et al., 2007) Another
coin from Dyrrachium (Durrës) of the III-II century
B.C. was determined to be a copper-tin-lead alloy
produced in a similar way compared with the coins
mentioned above. One nail from Dyrrah used in
land (IV-III B.C.) and one from Saranda used in a
ship (VI-IV B.C.) resulted pure copper which were
hot worked after being casted. (Dilo et al., 2009) A
necklace (VII-VI B.C.) and a belt application (VII-VI
B.C) from Shkodra were casted copper-tin-lead alloys while a button (VI-IV B.C) from the same region
resulted a casted copper-tin composition. (Çakaj et
al., 2014) Some weapons were studied as well such
as six swords, three spearheads and a shield from
the south-west and south-east of Albania. The shield
from Apollonia (Fier, south-west Albania) was a
copper-tin alloy produced throught hot working after casting. While one sword from Erseka (south-east
Albania), five swords of type Naue II and three
speardheads from Korça (south-east Albania) resulted copper-tin alloys. (Koui et al., 2006; Çakaj et al.,
2009) Also some copper alloy sculptures from Antigonea have been studied for restoration and conservation reasons. (Budina and Stamati, 1989)
SCIENTIFIC CULTURE, Vol. 2, No 2, (2016), pp. 9-18
Fibula and snake bracelet from Albania. a case study by om, SEM-EDS and XRF
11
b)
a)
Figure 1. a) Political map of the Balkan Peninsula and the Near East. It shows ancient copper mines in Serbia (Rudna
Glava), Bulgaria (Ai Bunar), Lavrion (Greece); copper rich regions in Cyprus and in northern Albania (Mirditë). This
study objects were found in Scodra and in Dyrrachium.
(http://www.worldatlas.com/webimage/countrys/europe/balkans.htm). b) The extension of FeS 2-CuFeS2 and FeS2CuFeS2-(Zn,Fe)S ores in Albania. Regions rich in copper ores (Mirditë, Rubik), objects’ excavation locations (Scodra,
Dyrrachium), excavation locations of former studied objects (Shkodra, Durrës, Saranda, Apollonia, Antigonea, Erseka,
Korça), the Albanian capital (Tirana). (Economou-Eliopoulos, Eliopoulos, and Chryssoulis 2008.)
2. MATERIALS AND METHODS
Sample from the fibula and the snake bracelet
was removed using a small pincers and in both cases
it didn’t exceed 6mm3 in volume (Figure 2a). The
sampling process was carefully carried out in order
to have almost no impact on the object integrity and
to collect as much information as possible. The fibula
(IX-VIII BC Iron Age, object no. 17960, code 015, file
no. 485) dates back to the Iron Age and has a spiral
string that forms two round discs 0.065m in diameter
connected together (0.145m length from one side to
the other) while each disc has a conical button on the
centre (the two discs found separated in the excava-
tion). This fibula has no visible clip on the back side
and its total length is approximately 2.3m. The snake
bracelet (III-I BC. Hellenistic Period, object no. 60205,
code 029, file no. 9786) comes from the Hellenistic
Period, has a diameter of 0.047m, the height of spirals is 0.032m and the total length is 0.7m. The cross
section of the fibula is 3.2∙10-6m2 and the one of the
snake bracelet is 4∙10-6m2. Both objects have no visible defects and the cross section is approximately the
same along the whole length. (Prendi 1958, 2008)
Figure 2a) shows the objects’ photos while 2b) shows
their sketches.
b)
a)
Figure 2. a) Photos of the fibula (left), the snake bracelet (right) along with the positions where each sample was taken,
b) the corresponding objects’ sketches.
The examine procedure starts with µ-X ray
fluorescence (µ-XRF) performed on 2-3 spots of the
objects’ cleaned surface (without varnish) to determine the alloy composition, taking account that the
objects are chemically homogeneous. The equipment
used was transportable µ-XRF spectrometer ARTAX
Bruker (60μm spot diameter, detective capacity from
Na to U) with Spectra ARTAX Version 7.2.5.0 and
M-Quant-Calib (BRUKER) software. After this the
samples (less than 12∙10-9m3) were prepared
through mounting in epoxy resin, polishing with SiC
paper (30μm, 18μm, 5μm) and cloth with diamond
paste (3μm, 1μm)associated with DP-Lubricant Blue.
Vickers tester (attached on the Metalloplan Leitz microscope) was used to measure the microhardness
values of the samples. Kozo XJP304 optical microscope (OM) with reflected and polarized light along
with Sony TCC-8.1 digital camera and View Version
7.3.1.7 image analysis software were used to observe
the corrosion products and the microstructure.
Scanning electron microscope-energy X ray dispersive spectroscopy (SEM-EDS) XL30 ESEM-FEI with
SCIENTIFIC CULTURE, Vol. 2, No 2, (2016), pp. 9-18
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Olta Çakaj et al
EDAX Genesis Spectrum software was used to study
the microstructure’s inclusions / secondary phases.
In order to observe the microstructure the samples
were etched with aqueous ferric chloride solution
(H2O : HCl : FeCl3 = 12ml : 3ml : 1gr) for several seconds. (Goldstein et al. 2003; MIT 2003; Potts & West
2008; Wayne 2009).
sion products. The metal spots on the fibula were
chosen randomly while in the snake bracelet case,
the first examine was performed on the snake head
meantime the other on the bottom edge. Figure 3
shows the μ-XRF spectra of the first spot examined
on each sample while table 1 lists the chemical elements’ quantitative results with the corresponding
standard deviations for all the analysis.
3. RESULTS AND DISCUSSIONS
For each of the objects were chosen two spots on
the cleaned metal surface and one spot on the corro-
a)
b)
Figure 3. μ-XRF spectra of the first metal spot examined on a) the fibula and b) the snake bracelet. The alloy results Cu and Sn with
minor elements such as Pb, Fe, Ni, As and Cr.
Table I. µ-XRF results (elements percentage with the
standard deviation) for a) the fibula and b) the snake
bracelet.
a) Fibula (IX-VIII BC)
Element
Metal spot 1
Metal spot 2
Corrosion spot
Cu (%)
Sn (%)
Pb (%)
Fe (%)
Ni (%)
As (%)
Ca (%)
Cr (%)
91.79±2.66
6.35±0.38
0.95±0.08
0.55±0.02
0.21±0.01
0.16±0.04
–
–
90.95±4.28
6.93±0.6
1.34±0.16
0.42±0.03
0.18±0.02
0.18±0.07
–
–
28.5±0.8
53.49±1.91
5.57±0.33
3.33±0.11
0.32±0.02
1.71±0.17
7.07±2.84
–
b) Snake bracelet (III-I BC)
Element
Cu (%)
Sn (%)
Pb (%)
Fe (%)
Ni (%)
As (%)
Ca (%)
Cr (%)
Metal spothead
89.11±4.3
9.05±0.76
1.55±0.12
0.24±0.02
–
–
–
0.04±0.01
Metal spotbottom
88.26±3.32
9.46±0.65
2.06±0.12
0.21±0.01
–
–
–
–
Corrosion spot
55.77±1.78
37.68±1.69
6.04±0.25
0.5±0.03
–
–
–
–
From the μ-XRF data obtained the fibula and the
snake bracelet resulted copper-tin alloys with lead
content around 1.14% and 1.8% respectively. The tin
percentage in the fibula’s alloy is around 6.64% and
the one in the snake bracelet is around 9.25%. Other
chemical elements such as Fe, Ni, As and Cr present
less than 0.6% in the metallic alloys may originate
from the soil content where the objects were preserved through the centuries or from the mineral
used for the alloy production. According to the CuSn phase diagram (usual casted condition) the alloy
at low temperatures and low tin percentage is composed by α and δ eutectoid phases. The Cu31Sn8 δ
phase is a crystalline solid intermetallic compound
which tends to be very hard with no ductility. The
composition of Cu and Sn in the δ phase is fixed
(Cu:Sn=67.47%:32.53%) while the α phase can absorb
more or less Sn according to the alloy consistence.
Furthermore for bronzes with tin between 5-10% the
adding of lead makes the alloy less viscous. For very
low lead content such as this study objects the increase of the tin percentage causes the decrease of
the material ductility or the elongation value (fibula
40%-50% and snake bracelet 20%-30%). (Scott 2012)
The Cu percentage decreases in the outer surface
while Sn percentage increases because of their different diffusion coefficients and the formation of corrosion products of both elements (oxide and hydroxide). (Dillmannet al. 2007) On the corrosion spots
oxygen is not detectable with μ-XRF and its percentage is added by the software to the other present
detectable elements (overestimation) in order to
have a total of 100%. This can be observed in the μXRF results of the corrosion spots analysed on each
sample. Figures 4, 5 show the corrosion products
observed with polarized light OM for the fibula’s
sample and the snake bracelet’s one respectively.
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Fibula and snake bracelet from Albania. a case study by om, SEM-EDS and XRF
Figure 4. Fibula’s corrosion products, photo obtained using OM with crossed nicols polarized light (left) and parallel
nicols polarized light (right). Corrosion products introduced far inside the alloy. Present main phases that differ in
colours are CuO, Cu2O and Cu2CO3(OH)2.
Figure 5. Snake bracelet’s corrosion products, photo obtained using OM with crossed nicols polarized light (left) and
parallel nicols polarized light (right).Corrosion products introduced far inside the alloy. Present main phases that differ
in colours are CuO, Cu2O and Cu2CO3(OH)2.
It is clear from figures 4, 5 that the corrosion
products are introduced far inside the alloy. Different colours are visible on the polarized light OM
photos (crossed nicols) for both samples such as
bright and dark red mixed with brown areas overlapped by bright and dark green. The observation of
corrosion for both samples (figure 4, 5) leads to the
conclusion that the objects are authentic (not fake
replicas) because of these products’ introduction far
inside the alloy which can’t be done artificially in a
short time.
Based on the different corrosion colours from the
OM crossed nicols polarized light photos the main
phases present might be tenorite CuO (brown), cuprite Cu2O (red) from the first corrosion layer and
malachite Cu2CO3(OH)2(green) from the second one.
(Pracejus 2008) The first corrosion layer is formed
during the production process and the object’s usage. It is mainly composed by tenorite CuO (dark
brown with red internal reflections), cuprite Cu2O
(bright/dark red) and SnO / SnO2 / Sn(OH)2 (grey
colour shades). The second corrosion layer overlaps
the first one and appears during the end of the usage
period. The distinguish green colour comes from
malachite Cu2CO3(OH)2 but also from nantokite
CuCl and antlerite Cu3SO4(OH)4. When the percentage of CO2 is high in contact with the object other
phases are formed such as azurite Cu3(CO3)2(OH)2
(blue) and cerussite Pb2CO3(OH)2 (light grey). Last
comes the third corrosion layer which is formed during the object’s burial and includes compounds from
the surrounding soil. The corrosion phases can be
identified with XRD analysis or the main ones that
differ in colours can be specified through observing
the corrosion products with a microscope (polarized
light) along with an optical mineralogical manual.
(Vink 1986; Pracejus 2008; Sandu et al. 2008, 2014).
Table 2, 3 shows the EDS results of all examined
areas and points for the fibula’s and snake bracelet’s
sample.
Table 2. EDS results for the fibula (mean value of standard
deviation ±0.3%).
Element
Cu (%)
Pb (%)
O (%)
Sn (%)
S (%)
Fe (%)
Point A
08.00
86.53
05.46
–
–
–
Area B
91.81
–
–
08.19
–
–
Area C
65.36
–
–
–
25.67
08.97
Area D
06.62
53.81
21.67
10.83
07.07
–
Table 3. EDS results for the snake bracelet (mean value of
standard deviation ±0.3%).
Element
Cu (%)
Pb (%)
O (%)
Sn (%)
S (%)
Fe (%)
Area A
61.84
29.31
–
07.07
01.78
–
Area B
91.24
–
–
08.76
–
–
Point C
79.21
–
–
–
19.42
01.37
Figures 6, 7 show the SEM images of with the
EDS examined areas or points along with the corresponding spectra for both samples.
SCIENTIFIC CULTURE, Vol. 2, No 2, (2016), pp. 9-18
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Olta Çakaj et al
Figure 6. Photos obtained with SEM of the fibula’s sample along with the EDS area/point analysis and spectra. The
bright inclusions are rich in Pb while the dark ones are Cu-Fe-S inclusions. The alloy is composed by Cu-Sn and the
corrosion area contains oxidised Cu, Pb, S and Sn.
Figure 7. Photos obtained with SEM of the snake bracelet’s sample along with the EDS area/point analysis and spectra.
The bright inclusions are rich in Pb but also S while the dark ones are Fe-S inclusions. The alloy is composed by Cu-Sn.
In both samples the EDS examination on the alloy
(area B in both objects) confirms the μ-XRF results
taking account the standard deviation as well. Bright
and dark inclusions are visible in the SEM photos of
both alloys. After the EDS analysis all the bright inclusions resulted rich in Pb while all the dark ones
are mainly composed of Cu-Fe-S. Although only one
EDS analyse of these inclusions for each sample is
shown in this study.
If the analysed area/point is smaller than 5μm
(the average dimension of the interaction volume) is
probable that the detection of the alloy elements Cu
and Sn comes from the surrounding area. This is the
case of the examined point A on the fibula sample
and area A / point C on the snake bracelet sample.
Only one corrosion area was analysed on the fibula
sample (area D) and among the chemical elements
(table 2) were also the ones detected with μ-XRF on
the corrosion products (table 1).
The present of Cu-Fe-S inclusions in the alloy
may be an indication of sulphide mineral usage in
the production procedure. This mineral mainly consists of copper sulphide and copper-iron sulphide
compounds that do not mix well with metallic copper and one of which is bornite Cu5FeS4. (Shugar
2003; Ashkenazi et al. 2012) A comparison between
the Cu-Fe-S experimental percentages of the fibula’s
area C with the elements’ weigh consistence in
Cu5FeS4 was made. Area C is composed by
65.36%Cu - 25.67%S - 8.97%Fe (table 2) while the
weight percentages of these elements in Cu5FeS4 are
63.32%Cu - 25.55%S - 11.13%Fe. This can suggest the
possible use of bornite in order to produce the fibula’s alloy. (Figueiredo et al. 2011)
SCIENTIFIC CULTURE, Vol. 2, No 2, (2016), pp. 9-18
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Fibula and snake bracelet from Albania. a case study by om, SEM-EDS and XRF
Table 4 shows the Vickers microhardness results
along with the mean value for both samples. The
fibula sample has a mean Vickers microhardness
value of 116.2HV while the snake bracelet’s one is
around 113.6HV (absolute error ±1HV). Adding additional chemical elements in copper (alloying) and
submitting the metal to different mechanical / thermal processes can increase the Vickers microhardness value from 40-50HV (pure casted Cu) up to
220HV (fully worked Cu-Sn alloy). For the same percentage of Sn the adding of Pb can slightly decrease
the microhardness and on the other hand it increases
after the order of the processes: casted → worked
and annealed → cold worked. (Scott 1991)
Table 4. Measured and calculated mean values of the
Vickers microhardness test (absolute error in measuring
the Vickers microhardness is ±1HV).
HV
Test 1
Test 2
Test 3
Test 4
Test 5
Test 6
Test 7
Mean value
Fibula (IX-VIII BC)
117
109
116
121
119
115
–
116.2
Snake bracelet (III-I BC)
123
121
114
115
107
109
106
113.6
Figure 8 a), b) and figure 9 a), b) show the fibula’s
and the snake bracelet’s respective microstructure
using OM with reflected light and SEM.
b)
a)
Figure 8. Fibula’s microstructure, photos obtained using: a) OM with reflected light etched for 1-2 seconds and b) SEM.
The OM photo reveals twins (1), strain lines (2) and (3) elongated / orientated δ phase in the microstructure while the
both OM - SEM photos show elongated / orientated Pb inclusions (4).
a)
b)
Figure 9. Snake bracelet’s microstructure, photos obtained using: a) OM with reflected light etched for 5 (above) and 7
(below) seconds and b) SEM. The OM photo reveals twins (1) and strain lines (2) in the microstructure while the SEM
photos show no texture.
According to the fibula’s OM reflected light photo the presence of twins and some strain lines (figure
8a) suggests that the alloy might have been firstly
casted then cold worked and at the end annealed
(hot worked). Another possible production process
starts with casting then annealing and last cold / hot
working. Adding Pb in Cu alloys increases the fluidity during casting but it’s not suitable in high percentage for bronzes that will be hammered because
lead can decrease the alloy ductility. This happens
because Pb is not soluble in Cu, it usually segregates
in grain boundaries and during hammering the
propagation of cracks can occur along Cu-Pb interfaces. It is clear from the OM and SEM figure 8 a), b)
that the Pb and Cu-Fe-S inclusions are elongated and
orientated in one direction evidencing a texture microstructure caused by probable hammering. Taking
into account that lead has a significantly lower melting point compared to copper, the most probable
production technique might be the one where the
alloy after casting has been hot worked in order to
obtain the object’s final shape. (Mortazavi et al. 2011;
Ashkenazi et al. 2012)
On the snake bracelet’s microstructure (figure 9a)
from the OM photos with reflected light are clearly
visible twins and strain lines. According to the literature the alloy has been initially casted, then it might
has followed these possible processes: 1) cold
worked, annealed and again cold worked at the end
or 2) hot and cold worked to obtain the final shape.
On the SEM photo (figure 9b) of the snake bracelet’s
sample no texture is visible, meaning that the Pb and
Cu-Fe-S inclusions have no orientation and are not
elongated in one specific direction.
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Olta Çakaj et al
Based on the literature after the alloy is casted the
microstructure is composed by dendrites (like fernlike growth) which can lead to bent ones after cold
working or to hexagonal grains after the alloy has
been annealed (hot worked). If the bent dendrites
microstructure is annealed (hot worked) a twinned
one will be obtained. On the other hand the twinned
microstructure can also derive from hot working the
hexagonal grains’ alloy. The increase of the alloy
strength from cold working is higher compared with
the one from hot working but in both cases the ductility of the material decreases. Further cold working
can bend the twins and create stain lines. (Scott 2012)
4. CONCLUSIONS
Different analytical methods were used in this
study in order to have the fibula’s and snake bracelet’s characterization as complete as possible.
From the μ-XRF examination both alloys are α +
δ phases Cu-Sn with the addition of low percentage
of Pb. The fibula is composed by 6.64% Sn and 1.14%
Pb meanwhile the snake bracelet has a higher consistence of the two elements respectively 9.25% Sn
and 1.8% Pb. Soil chemical elements are present in
both samples such as Fe, Ni, As, Ca, Cr.
The EDS results of the alloy area confirm the μXRF analysis. The SEM-EDS analysis show the presence of Pb and Cu-Fe-S inclusions. This result and
based on the geological - mineralogical studies of
Albanian copper ores brings to the assumption that
local sulphite minerals might have been used as raw
material.
According to the OM photos with polarized light
the first and second corrosion layer main phases are
present in both samples. Based on these products’
insertion far inside the alloy both objects result authentically antique ones.
The SEM and OM with reflected light photos
show the presence of twins, strain lines, orientated
elongated Pb and Cu-Fe-S inclusions, δ phase and
pores in the fibula’s microstructure. The presence of
twins and strain lines is very clear on the OM photos
with reflected light of the snake bracelet’s sample.
This might be explained if the objects after casting
have been hot worked probably by hammering and
then cold worked where the final shape has derived.
The Pb and Cu-Fe-S inclusions in the snake bracelet’s
sample (SEM photo) result not elongated and orientated. The Vickers microhardness value is 116.2HV
for the fibula and 113.6HV for the snake bracelet.
These objects are evidence of unique and distinct
handicraftsmen skills in metal processing since the
IX-VIII BC in Albania. By using simple tools such as
hammers and furnaces the handicraftsmen were able
to produce beautiful wire-like ornamental objects
with considerable length and no visible defects.
ACKNOWLEDGEMENTS
The authors are very grateful to the Archaeological Department, Historical Museum of Shkodra and the Institute of Cultural Monuments in Tirana for providing the objects for this study; the Centre of Applied Nuclear Physics, the Faculty of Natural Sciences, UT, Albania and the Institut für Keramik, Glas- und
Baustofftechnik, TU Bergakademie Freiberg, Germany for their support with analytical equipment and funding. The authors would like to thank DAAD for financially sustaining the analysis performed in Germany
and project coordinator Prof. Dr. Thomas Bier. Last but not least the authors are grateful for the unremitting
collaboration of Mr Zamir Tafilica (archaeologist) and Mrs Edlira Çaushi (restorer).
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