Small Size, High Value: Composition and Manufacture of
Second Millennium AD Copper-Based Beads
from Northern Zimbabwe
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Thomas Panganayi Thondhlana & Marcos Martinón-Torres
Abstract
Résumé
This investigation introduces a new dimension to the previous typological analyses of the metal bead assemblages
from Zimbabwean archaeological sites. Here we present
the microstructural and chemical characterisation of
50 copper-based metal beads from the collections of the
Zimbabwe Museum of Human Sciences (ZMHS) in Harare,
most of them from Later Farming Community period
sites in northern Zimbabwe (AD 1000 to AD 1900). The
analytical study employed optical microscopy, ED-XRF
and SEM-EDS.
Cette étude ajoute une nouvelle dimension aux analyses typologiques précédemment réalisées sur des assemblages de
perles métalliques provenant de sites archéologiques zimbabwéens. Nous présentons dans cet article la caractérisation
microstructurale et chimique de 50 perles en alliage à base de
cuivre qui proviennent des collections du Musée de Sciences
Humaines du Zimbabwe à Harare, la plupart étant originaires
de sites du nord du Zimbabwe et datant de la période dite des
« Communautés Agricoles Finales » (1000 ap. J.-C. – 1900
ap. J.-C.). Dans le cadre de cette étude analytique, la microscopie optique, la spectroscopie de fluorescence X à dispersion
d’énergie, et la microscopie électronique à balayage à dispersion d’énergie ont été utilisées conjointement.
Compositionally, unalloyed copper, arsenical copper and tin bronzes were identified in the earlier sites,
with some significant regional variations. From the
seventeenth century, brass becomes the preferred alloy.
The potential sources of these metals and their spatial
and temporal patterning are discussed with reference to
both the socio-economic dynamics prevailing in Zimbabwe during the period, and the symbolic value of metal
beads in these communities. The metallographic study
showed a preponderance of wrought beads, with a small
but significant presence of cast forms. These fabrication
technologies reflect little outside influence and are in line
with indigenous African metal smithing methods.
En termes de composition chimique, des cuivres non alliés, des cuivres à l’arsenic et des bronzes cuivre-étain ont été
identifiés sur les sites les plus anciens, montrant d’importantes variations sur le plan régional. A partir du dix-septième
siècle, le laiton devient l’alliage de prédilection. Les sources
potentielles pour ces métaux et leur distribution spatiale et
temporelle sont discutées, tenant compte des dynamiques
socio-économiques qui prévalaient au Zimbabwe à cette
époque et de la valeur symbolique des perles métalliques
dans ces communautés. L’étude métallographique a montré
la prépondérance de perles forgées par rapport aux formes
coulées, moins nombreuses, mais dont la présence est cependant significative. Ces techniques de fabrication ne reflètent
qu’une faible influence extérieure et sont en accord avec les
méthodes indigènes de travail du métal en Afrique.
Keywords: archaeometallurgy, Zimbabwe, Later Farming Communities, copper and copper alloys, technology, composition
Thomas Panganayi Thondhlana 8 [email protected] / Marcos Martinón-Torres 8 [email protected]
* Institute of Archaeology, University College London, 31-34 Gordon Square, London WC1H 0PY, United Kingdom.
DOI 10.3213/1612-1651-10119
Published online in February 2009
© Africa Magna Verlag, Frankfurt M.
Journal of African Archaeology Vol. 7 (1), 2009, pp. 79-97
79
T.P. Thondhlana & M. Martinón-Torres
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Introduction
Decades of archaeological excavations in northern
Zimbabwe have resulted in the accumulation of a fairly
large corpus of copper-based metal artefacts. These
artefacts came from a variety of sources, such as human burials, hoards and some represent occasional
accidental losses. The prevalence of these artefacts
confirms the observation that copper and its alloys
played a pivotal role in the spheres of politics, religion
and economics in most past African societies (Bisson
1975, 1997, 2000; Herbert 1984). These copper-based
artefacts were largely produced for non-utilitarian purposes in the form of jewellery. Noteworthy in Zimbabwean Iron Age contexts is the prevalence of metal
beads of various shapes and sizes. Previous stylistic
analyses have suggested a shift over time from simple
cylindrical and barrel-shaped beads to complex biconical and octahedral forms (Robinson 1959: 145–146;
Soper 2002: 161; Thondhlana 2005). Although these
studies have helped to illuminate diachronic changes,
some basic questions concerning these artefacts are yet
to be addressed, such as the sources of metal, alloys
employed, manufacturing techniques and technological
innovations, as well as the specific roles and uses of the
beads. These questions are particularly important if one
considers the lack of evidence for copper production
during the Farming Community period in most areas
on the Zimbabwe plateau (Soper 2002: 262), meaning that it remains unclear whether these beads were
manufactured locally. The main goal of this paper is
to employ archaeometallurgical investigations to address some of these questions, whilst increasing our
understanding of the economic, ideological, social and
political dynamics of the Later Farming Communities
in northern Zimbabwe. Though small in size, it will
be shown in this paper that these metal artefacts are
archaeologically informative.
Archaeologists have recognised the importance
of metal artefacts and metal working debris in the understanding of past societies and their technologies
in southern Africa (Childs 1991; Miller & van der
Merwe 1994; Miller, Boeyens & Küsel 1995; Childs
& Dewey 1996; Miller 1996, 2001, 2002; Chirikure
& Rehren 2004, 2006; Chirikure 2006). These technological studies have contributed immensely to mainstream archaeology. The present study was carried
out on the premise that the physical and mechanical
properties of material culture have a critical effect upon
their use and perception (Jones 2004: 331). This paper
therefore is not limited to discussions of techniques
and characterisation of materials but goes further to
ascertain the close link between human beings and
artefacts. According to Tilley et al. (2006: 2), tech-
80
nological studies should be concerned with deepening
our insight into how persons make artefacts and how
artefacts make persons in return. At the core of such an
objective is the concept of materiality, anchored on the
premise that the material or physical components of the
environment together with the related social practices
are mutually reinforcing, to the extent that they are
analytically indivisible (Jones 2004: 330). The processes of production and use of artefacts are embedded
in their socio-cultural context and as such they should
be studied together. Through making, using, exchanging, consuming, interacting and living with artefacts,
people make themselves in the process (Tilley 2006:
61). This paper thus contributes to the recent studies of
pyrotechnological materials in southern Africa, which
have strived to document the metal compositions and
fabrication techniques at Farming Community period
sites in the Tsodilo area in Botswana (Miller 1992,
1996) and in South Africa (Miller et al. 1995; Miller
2001, 2002), helping to fill the gaps in our knowledge
of pre-colonial copper metallurgy in southern Africa.
Brief site profiles and description of samples
The artefacts subjected to analyses in this study came
from fifteen Farming Community period sites in northern Zimbabwe and additional comparative materials
were sourced from two sites in southern Zimbabwe
(Fig. 1). These artefacts are part of the archaeological
collections held at the Zimbabwe Museum of Human
Sciences (hereafter ZMHS) in Harare, Zimbabwe. As
previously defined by Pikirayi (1993: 24), Northern
Zimbabwe comprises the northern extension of the
Zimbabwe plateau, a belt of highland over 1000 m
above sea level, and the adjacent middle and lowveld
areas with the Zambezi River marking the northern
limits. In the East and West, the Mazowe-Ruenya and
the Manyame-Angwa valleys form natural boundaries
and the modern city of Harare is taken as the arbitrary
southern boundary. In this work, samples were also
collected from sites west of the Angwa River in northwestern Zimbabwe. This section summarises the cultural groups and broad chronologies of the sites which
are discussed in this paper.
As a result of their repeated and structured design
sets, ceramics are the most useful tool in the development of Farming Community cultural sequences in
Zimbabwe (Huffman 1974: 1). The earliest known
ceramic unit of importance in this paper is Gokomere.
Cylindrical metal beads were recovered from several
early Gokomere Tradition contexts in southern Zimbabwe. They include ten beads from the site of Mabveni,
which possibly represent the earliest known copper
Journal of African Archaeology Vol. 7 (1), 2009
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Small Size, High Value
1490 ± 120 [SR-1259]) for Gadzema (Huffman 1971: 29). Contemporary pottery decorative styles to the north-east of the Harare
Tradition sites have been attributed to the
Musengezi Tradition (Huffman 1971; pwiti
1996; Burrett 1998; piKirayi 2001). Metal
beads were excavated at the Monk’s Kop
(Mbagazewa) ossuary of the Musengezi
Tradition. Two radiocarbon dates AD 1270
± 95 (SR-100) and AD 1285 ± 95 (SR-101)
are available for this multicomponent burial
site (Crawford 1967: 379). The beads from
this site were cylindrical in shape with some
striking similarities between themselves
which suggest some form of standardisation and mass production. Another bead was
collected from the Musengezi Tradition site
of Wazi (Soper & pwiti 1988). Archaeological evidence suggests that at the same time
the area to the west of the Angwa River was
occupied by Ingombe Ilede groups. These
Ingombe Ilede cultural groups appear to be
related to the Farming Community groups
in Zambia more so than their eastern counterparts (Huffman 1974: 3). An important
Fig. 1. Map of Zimbabwe showing the distribution of sites menfeature of the Ingombe Ilede groups was
tioned in the text. MUY (Muyove), RYD (Rydings), KAS (Kasekete),
their production and trade of copper (BurMYC (Matanda yaChiwawa), WAZ (Wazi Hill), CHE/W (Chenguruve
rett
1998). garlaKe (1970) excavated two
Hill East & West), BAR (Baranda), BRC (Beryl Rose Claims), MUH
Ingombe Ilede sites, Rydings (Chedzurgwe)
(Muchekayawa Hill), LUA (Luanze), RR (Ruanga Ruins), MK (Monk’s
Kop), AE (Arlington Estate), LO (Little Over), MAB (Mabveni), GZ
and Muyove which yielded one metal bead
(Great Zimbabwe).
each. The quantity of copper-based metal
beads from these sites supposedly associated
with renowned copper workers is surprisproducts on the Zimbabwe Plateau (Swan 1994), alingly very low, considering the fact that 162 sites with
though some scholars question the status of these beads
cross-shaped copper ingots were recorded in this area
as the earliest evidence of copper production in Zim(Swan 1994: 25, 2007). The same scenario was also
babwe (see miller 2003). Two calibrated radiocarbon
noted at the Ingombe Ilede burials (type site) where,
dates are available for the site of Mabveni: AD 180
despite extensive excavations, only five copper beads
± 120 (SR-43) and AD 570 ± 110 (SR-79) (Huffman
were recorded (fagan et al. 1969: 72).
1980). A metal bead was recovered from Little Over,
a site assigned to the Maxton phase of the Gokomere
From the fifteenth century we see the appearance
Tradition. Elsewhere, at Coronation Park in northern
of Zimbabwe Tradition groups in northern Zimbabwe
Zimbabwe, Maxton pottery has been dated to AD 980
(pwiti 1996: 153). This development may have been
± 100 (N-979) (Huffman 1971: 28). Three cylindrical
linked to the demise of the Great Zimbabwe State in
metal beads from Mabveni and Little Over were sethe South (piKirayi 2001). There have been suggestions
lected from the ZHMS museum collections for further
that the decline of the Great Zimbabwe State was partly
study.
caused by Ingombe Ilede groups in northern Zimbabwe
who took control of the intraregional trade of copper
Samples were also collected from a Harare Tradiand other metals, depriving their southern neighbours
tion burial in the Arlington Estate which yielded metal
of their earlier interests (pwiti 1991; piKirayi 2001).
beads in the form of bicones, barrels and cylinders.
Metal beads and artefacts were also collected from five
There are no absolute dates for the site, however related
Zimbabwe Tradition sites. These included Kasekete
Harare Tradition burials date between the thirteenth
and Matanda yaChiwawa, both located in the middle
century (AD 1270 ± 60 [GRN-2341]; AD 1280 ± 100
Zambezi Valley (pwiti 1996: 77), Ruanga, a zimbabwe
[Y-722]) for Graniteside to the fifteenth century (AD
dry-stone structure (garlaKe 1972), Beryl Rose Claims
Journal of African Archaeology Vol. 7 (1), 2009
81
T.P. Thondhlana & M. Martinón-Torres
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(Pikirayi 1998) and Baranda (Pikirayi 1993). Cylindrical shaped beads dominated all of these Zimbabwe
Tradition sites in northern Zimbabwe. For comparative
purposes, beads were also collected from the zimbabwe
type site of Great Zimbabwe in the south-central part
of Zimbabwe.
By the sixteenth century Afro-Portuguese trading
settlements or Feiras were established in the eastern
part of northern Zimbabwe. These lasted up until the
1690s, when most of the Portuguese were expelled
from northern Zimbabwe (Huffman 1971: 41; Pikirayi
1993: 113). Metal beads from Luanze, an important
Portuguese period site were also collected for further
laboratory studies. Contemporary to the Portuguese
period settlements in northern Zimbabwe is the indigenous archaeological entity known as the Mahonje
Tradition, with dates between the seventeenth century
and the nineteenth century. Mahonje Tradition sites
are characterised by loopholed stone-wall fortifications, often located in inaccessible high grounds that
reflect defensive locations against violent Portuguese
activities and those of competing local groups (Pikirayi
1993, 1996, 2001: 182). A total of fifty-two metal beads
were excavated from three Mahonje Tradition sites,
namely Chenguruve Hill East, Chenguruve Hill West
and Muchekayawa Hill, all of which are located in the
middle Mazowe River basin (Pikirayi 1993: 156). The
majority of these were small biconical beads made from
short triangular cross-section wire (Soper 2002: 262).
A dozen of beads were collected from these Mahonje
Tradition sites for further analyses.
However, details of heavily tarnished and corroded articles could not be established by this method.
Energy Dispersive X-Ray Fluorescence Spectrometry
(ED-XRF): ED-XRF was used in this study as a screening non-invasive technique, to obtain a first assessment
of the chemical composition of the beads. The analyses
were performed with a Spectro X-Lab Pro 2000, using
three polarising secondary targets and an evaluation
method optimised for alloys. Given the small size of
the beads (typically <10 mm, compared to the detector
window of 25 mm), and the fact that they were placed
in the chamber without any preparation or removal of
corrosion patinas or encrusted soil, these results can
only be reported as qualitative. The analytical totals for
this type of analyses were in the range of 10 %, which
highlights the low accuracy of the results. Comparisons
between XRF and SEM-EDS results performed on the
same beads also showed significant discrepancies.
However, this technique was useful as a way of
screening a relatively large number of artefacts (~50),
to discriminate between alloys and to assess whether
the results from the beads analysed by SEM-EDS could
be extrapolated to the rest of the samples in the same
type category. In addition, thanks to the low detection
limits of this technique, the presence/absence of some
trace elements could also be determined on a qualitative basis.
Artefacts selected from the archaeological collections
held at ZMHS were subsequently subjected to laboratory studies at the Wolfson Archaeological Science
Laboratories of the UCL Institute of Archaeology in
London, using the methods described below.
Reflected-light Microscopy: Metallographic analysis of a number of these metal artefacts was carried
out to understand their fabrication techniques. Metals
are made up by minute crystals with distinct shape,
structure, alignment and size. The factors controlling
the microstructure of metals include, among others,
their composition and fabrication processes (Bailey
1982: 32). Thus, analyses of the microstructure of metal
objects indicate their composition and technological
history. To study these crystals at microscopical level,
polished metal surfaces were required.
Stereomicroscopy: The surface morphology of the metal
articles is a crucial element in the understanding of
their construction. Initial laboratory work involved the
inspection of specimens under low magnification to
reveal details not readily visible to the naked eye. A
stereoscopic microscope with a camera attachment was
used for a first assessment of manufacturing technology,
surface appearance and tool marks. This microscope offers the necessary depth of field which is useful in the establishment of three-dimensional features of specimens
(Ogden 1992: 20). Surface features of the specimens
sought and captured on camera included striations, gas
cavities, signs of wear, tool marks and seam treatments.
With permission from the ZMHS, 15 beads were
sampled invasively for metallographic study. A jeweller’s saw was used to remove these specimens, which
were mounted in epoxy resin and subsequently ground
and polished to a ¼ µm finish. A Leica DM LM polarised reflected light optical microscope equipped with
a digital camera was used to capture features such as
phases, inclusions, grain structure and size, defects like
shrinkages and porosity. For some specimens, the grain
structure was revealed by selective intergranular corrosion; however, in some cases it was necessary to etch the
polished blocks, using ferric chloride with 20 % HCl,
after the SEM-EDS analyses.
Analytical methods
82
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Small Size, High Value
Scanning Electron Microscopy with Energy Dispersive
X-Ray Spectrometry (SEM-EDS): Detailed characterisation of a number of artefacts was carried out with a
scanning electron microscope equipped with an energy
dispersive spectrometer. The SEM uses electrons to
generate images with better resolution at high magnification, whilst the EDS system allows compositional
analyses to be carried out on very small areas or phases
of the sample. The sampling size for invasive quantitative analyses was limited by the need to preserve
the artefacts in line with the conditions given by the
ZMHS. Therefore, SEM-EDS was used on both the
metallographic polished blocks (following carboncoating to reduce charging), and on complete beads. For
the complete beads, a ~1 mm2 area was abraded with
a 4000 grade polishing paper to remove the patina and
reveal the underlying sound metal matrix.
A Hitachi S-3400N instrument, with an INCA
Oxford energy dispersive spectrometer (EDS) was used
for the analysis. This instrument was used at the following working conditions: working distance 10 mm;
excitation voltage of 20 kV; probe current of 56.4–64.3
and a detector deadtime of 35–45 %. To enable valid
composition comparisons between specimens, compositional analyses were systematically carried out
by measuring three areas of 160 by 112 μm on each
sample. SEM-EDS values reported here are averages of
these three measurements, expressed as weight percent
and normalised to 100 %. Unlike ED-XRF, SEM-EDS
was carried out on sound metal, and thus the composition of different phases and inclusions was established
with more confidence. As discussed below, the concentration of zinc in brass beads was considered crucial for
subsequent interpretations, and thus a certified brass
standard (35.7 % Zn) was analysed to check the accuracy of the instrument. The relative error for zinc was
found to be of only 3.1 %.
Analytical results
Sample
Code
Type
Cu Zn Sn Co Ni As Ag Sb Au Pb
Gokomere Tradition
MAB 1 Cylinder
MAB 2 Barrel
LOM 1 Cylinder
●
○ ○ ○
●
● ○ ○ ○
● ○ ● ○ ○ ○
○
○
●
○
Musengezi Tradition
WAZ 1 Disk
○ ○ ○ ○ ○
Harare Tradition
AE 1
AE 2
AE 3
AE 4
AE 5
AE 11
AE 12
Barrel
Barrel
Barrel
Bicone
Cylinder
Bicone
Cylinder
●
●
●
●
●
●
●
○ ○ ○ ○ ○
○ ○ ○ ○ ○
○ ○ ○
○
○
○
○ ○
○ ○
● ○ ○
○
○
○
Ingombe Ilede Tradition
MUY 1 Ring
RYD 1 Cylinder
●
● ○
○
● ○
○ ○ ●
○
○
○
Zimbabwe Tradition
GZ 1
MYC 1
MYC 2
MYC 3
BAR 2
BAR 3
BRC 1
BRC 2
BRC 3
BRC 5
BRC 6
BRC 7
BRC 8
BRC 9
RR 1
RR 2
RR 3
RR 4
Bicone
Cylinder
Barrel
Cylinder
Cylinder
Pendant
Octahedral
Barrel
Cylinder
Cylinder
Cylinder
Cylinder
Cylinder
Ring
Cylinder
Cylinder
Cylinder
Cylinder
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
○
○
○
○
○
○
○
○
○ ○
○
● ○
○ ○
● ○
● ○
● ○
● ○
○
● ○
● ○
● ○
● ○
○
○ ○
● ○
● ○
● ○
○
○
○
○
○
○
○
○
○
○
○
○
●
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○ ○
○
○ ○
○ ○
○
○
○
○
○
○
○ ○
○ ○
○
○
○
○
○ ○
○ ○
○
○
○
○
○ ○
○
○ ○
○
○ ○
○
○ ○
○
○
○
○
○
○
○
Portuguese Tradition
LUA 1
LUA 2
LUA 3
LUA 5
Barrel
Barrel
Barrel
Barrel
●
●
●
●
○ ○
○
○ ○ ○ ○ ○
○ ○
○
○
○
○
○
○
○
○
○
○
○ ○
○
○
○
○
○
○
○
○ ○ ○
○
○ ○
○ ○ ○ ○ ○
●
○
○
●
○
○
○
○
○
○
○
○
○
○
○
○
○
○
Mahonje Tradition
Gokomere Tradition materials (2nd–11th century AD)
Artefacts in this group included a single cylindrical
bead (LOM1) from Little Over, a site assigned to the
Maxton phase of the Gokomere Tradition, and two
beads (MAB1 and MAB2) from the site of Mabveni,
which possibly represent the earliest known copper
products on the Zimbabwe Plateau (Swan 1994: 26).
These three well-preserved beads were initially analysed with ED-XRF (Tab. 1), which revealed that one
was made of pure copper, whilst the other two were
bronzes. Further SEM-EDS of these beads confirmed
the presence of relatively high tin bronzes (Tab. 2). As
CHW 1
CHW 2
CHW 3
CHW4
CHE 1
CHE 2
CHE 3
CHE 4
CHE 5
MUH 1
MUH 2
MUH 4
Bicone
Bicone
Bicone
Bicone
Bicone
Bicone
Bicone
Bicone
Bicone
Cylinder
Barrel
Bicone
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
Tab. 1. Qualitative results of the ED-XRF compositional analyses of copper-based artefacts from archaeological sites in
Zimbabwe (Legend: ●= major elements; ○= trace elements).
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T.P. Thondhlana & M. Martinón-Torres
Sample
Code
Type
MAB 1*
MAB 2*
MK 1*
MK 2
MK 3*
MK 11
MK 27
MK 28
MK 29
AE 1*
AE 11
AE 12
AE 13*
MUY1*
RYD 1
GZ 1
BRC1*
BRC 5
KAS 1
MYC 4
LUA 1*
CHW 1
CHW 2*
CHE 1*
MUH 3
MUH 4*
Cylinder
Barrel
Cylinder
Cylinder
Cylinder
Cylinder
Cylinder
Cylinder
Bicone
Barrel
Cylinder
Bicone
Bicone
Ring
Cylinder
Bicone
Octahedral
Cylinder
Cylinder
Debris/Lump
Barrel
Bicone
Bicone
Bicone
Barrel
Bicone
Broad
chronology S
(centuries
AD)
2nd–7th
2nd–7th
12th–14th
12th–14th
12th–14th
12th–14th
12th–14th
12th–14th
12th–14th
13th–15th
13th–15th
13th–15th
13th–15th
15th–16th
15th–16th
13th–15th
16th–17th
16th–17th
14th–16th
14th–16th
16th–17th
17th–19th
17th–19th
17th–19th
17th–19th
17th–19th
Fe
0.7
0.7
0.7
0.9
0.6
1.4
0.6 0.2
Cu
100.0
88.2
93.1
93.1
94.1
94.9
90.0
98.2
90.7
100.0
92.7
100.0
100.0
97.5
98.5
98.7
77.9
88.3
100.0
98.1
100.0
63.1
66.9
63.4
94.1
58.7
Zn As Sn Pb
11.8
6.2
6.2
5.3
5.1
9.2
1.8
8.7
Musengezi Tradition materials (12th–16th century AD)
7.3
2.5
1.5
1.3
20.7
11.7
1.2
36.5
33.1
36.6
3.1
41.3
0.4
2.8
Tab. 2. Bulk SEM-EDS results of the abraded surfaces samples*
and prepared polished blocks (Results presented as wt% and normalised to 100 %).
Fig. 2. Strikingly similar beads from the Musengezi Tradition site
of Monk’s Kop (Mbagazewa).
84
discussed in the next section, this composition
is not consistent with the known copper-based
artefacts from the first millennium AD archaeological contexts in southern Africa, where it has
been suggested that tin bronzes only appear in
the second millennium AD (miller et al. 1995;
miller 2003).
The largest assemblage of metal beads in northern Zimbabwe was excavated at the Monk’s Kop
(Mbagazewa) ossuary. The beads from this site
were mostly cylindrical and barrel in shape (Fig.
2). Most of the Musengezi Tradition materials were
in a bad state of preservation, and thus initial stereoscopic and ED-XRF analyses were inconclusive.
To compensate for this, seven specimens (MK1,
MK2, MK3, MK11, MK27, MK28 and MK29)
from Monk’s Kop were subjected to SEM-EDS
analyses after the removal of corrosion products.
The SEM-EDS results revealed that they were tin
bronzes with significant traces of iron (Tab. 2), and
containing few inclusions. Metallographic analyses
showed important fabrication information. For example the etched section of bead MK2 revealed deformed grains and strain lines, suggesting that there
was heavy working after annealing (SCott 1991:
8). The seam of the same specimen was unique,
consisting of a straight edge with vertical striations
parallel to it (Fig. 3). Thus it is likely that the seam
was not hammered into shape, but that a tong was
used from the outside to squeeze together the metal
ends to meet. The other four specimens showed a
well developed recrystallised structure with twin
lines, indicating that the beads were annealed after
cold-working (SCott 1991: 7). Unlike the MK2
specimen, the metallographic analyses of the seams
of these four beads revealed compressed grains at
the edge of the metal strip (Fig. 4). This grain compression is associated with the oblique cutting with
a chisel (miller & Van der merwe 1994: 108).
A single disc bead was recovered from the
Wazi Hill, another Musengezi Tradition site (Soper & pwiti 1988). This is the only disc bead known
from northern Zimbabwe; however, similar disc
beads are prevalent in western Zimbabwe Later
Farming Community contexts (roBinSon 1959:
145; tHondHlana 2005). ED-XRF analyses of the
Wazi disc bead show copper as the main element,
but they also reveal potentially significant levels
of arsenic (Tab. 1). However, considering the accuracy levels discussed above, further analyses
Journal of African Archaeology Vol. 7 (1), 2009
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Small Size, High Value
250 µm
250 µm
would be needed to confirm this alloy as arsenical copper. Indeed, in the bead BRC5 from Beryl Rose Claims,
discussed below, ED-XRF results indicated similar
traces of arsenic, but subsequent SEM-EDS of sound
metal showed no significant levels of this metal.
Harare Tradition materials (13th–15th century AD)
Beads from the Harare Tradition burial at Arlington Estate were relatively larger and heavier than those from
other sites in northern Zimbabwe. The bead assemblage
Fig. 3. Longitudinal section of cylindrical bead
(MK2), unetched, showing deformation of the
outside part of the seam
as the metal ends were
squeezed together. Photomicrograph under plane
polarised light (50x).
Fig. 4. Section of cylindrical bead (MK11),
unetched, showing grain
deformation caused by
cutting the edge with a
chisel. Photomicrograph
under plane polarised
light (50x).
from this site included well preserved bicones, barrels
and cylinders. Initial qualitative chemical characterisation of seven beads with the ED-XRF indicated that the
majority of these beads were nominally pure coppers
(Tab. 1). This pattern was confirmed through SEMEDS of four samples (Tab. 2). Another highlight of
the compositional results was the lack of traces of zinc
and lead, elements found in many beads from other
sites (Tab. 1).
Metallographic analyses of two beads (AE 11
and AE 12) revealed prominent longitudinal cracks
Journal of African Archaeology Vol. 7 (1), 2009
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T.P. Thondhlana & M. Martinón-Torres
250 µm
25 µm
within the well-preserved metal matrix (Fig. 5).
These cracks were certainly not caused by corrosion
because they do not show any penetration of corrosion products, and are therefore likely to originate
from the manufacturing process. Midsection cracking
of this nature is often associated with overworking,
and it is difficult to remove with further annealing and
working (SCott 1991: 101). This was also supported
by the examination of etched sections, showing slip
lines resulting from cold working in the final stage
(Fig. 6).
86
Fig. 5. Section of cylindrical bead (AE11), unetched,
showing internal deformities.
Photomicrograph under plane
polarised light (50x).
Fig. 6. Section of cylindrical
bead (AE11), etched in ferric
chloride solution, showing
slip lines. Photomicrograph
under plane polarised light
(500x).
Ingombe Ilede Tradition materials (15th–16th century AD)
Two well preserved beads (MUY1 and RYD1) were
excavated from two Ingombe Ilede sites, Rydings and
Muyove (garlaKe 1970). The ‘bead’ from Rydings,
formed by spiral turns, possibly represents a fragment
of a heavy bangle. The bead from Muyove can best be
classified as a ring rather than a cylinder because of
its short length. Both ED-XRF and SEM-EDS results
showed that the two beads were made of arsenical copper (Tabs. 1 and 2). In our current state of knowledge,
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these compositional results only have parallels with
specimens from the site of Great Zimbabwe, in southern Zimbabwe (Tab. 2). Noteworthy is the suggested
trade of copper from Ingombe Ilede metal workers to
Great Zimbabwe during the period under consideration
(Walsh 1997), which might explain this finding and
thus deserves further attention. However, the inclusion
chemistry of the Ingombe Ilede arsenical copper beads
differed from the Great Zimbabwe specimens. One
biconical bead (GZ1) from Great Zimbabwe contained
elongated bismuth and copper sulphide inclusions,
whereas the specimen (RYD1) from Rydings contained
numerous lead globules (Tab. 3).
Metallographic analysis of the arsenical copper
beads was not possible because the etching process
was not successful. However, the stereomicroscopy
investigation of a bead (MUY1) from Muyove also
provided an important insight into the fabrication technology. It was established that there were variations
in the thickness and absence of longitudinal striations
on the square-sectioned wire used in the manufacture
of this bead, which suggests that it was made with the
wrought technique, rather than by drawing (see below
for comparison).
Zimbabwe Tradition materials (14th–17th century AD)
Metal beads and artefacts were also collected from five
Zimbabwe Tradition sites of Ruanga Ruin, Beryl Rose
Claims, Baranda, Matanda yaChiwawa and Kasekete.
Although cylindrical beads dominated at these sites,
materials collected for analyses also included a unique
pendant from Baranda, two non-ferrous metal lumps
from Matanda yaChiwawa and an octahedral bead from
Beryl Rose Claims (Figs. 7–9). Beads from the site of
Great Zimbabwe were also analysed for comparison
(Fig. 10).
Both ED-XRF and SEM-EDS compositional analyses of the Zimbabwe Tradition samples from the North
revealed the incidence of pure copper beads, but also
the abundance of relatively high-tin bronzes. Potentially noteworthy are also the generally higher traces
of other elements, including zinc, nickel, arsenic, silver
and lead, which (although not reported quantitatively
here) differentiate these beads from those of sites predating the Zimbabwe Tradition in northern Zimbabwe
(Tabs. 1 and 2). These compositions also differ from
the analysed bead from Great Zimbabwe (GZ1), which
consists of arsenical copper (Tab. 2).
Metallographic analysis could not be carried out
on unique specimens like the pear-shaped pendant from
Baranda (BAR3), or the octahedral bead from Beryl
Rose Claims (BRC1), although both of them clearly
constitute cast bronze artefacts (Figs. 7 and 9). The
latter bead is strikingly similar to others reported from
contemporary Nyanga Complex sites of Leaping Waters and Matinha in the Eastern Highlands of Zimbabwe
(Soper 2002: 262). Another unique specimen which
was not analysed metallographically is the copper bead
MYC1 from Matanda yaChiwawa. Stereomicroscopic
examination of this bead showed the remnants of a
casting sprue (Fig. 11). The shape of the bead, together
with the absence of flash lines, makes it implausible
that it could have been cast by any method other than
lost-wax. Although cast copper and copper alloy beads
are very rare, locally-made cast gold beads have been
recorded at several second millennium AD sites in
southern Africa (Oddy 1984, 1991).
The metallographic study of beads BRC5 and
KAS1 showed twin lines on recrystallised grains, indicative of working and annealing. The latter bead
contained a good number of copper sulphide inclusions. Finally, one of the two amorphous lumps of metal
found at Matanda yaChiwawa, of approximately 2 cm
in diameter, was also analysed. This consisted of copper
containing small amounts of tin (1.2 %) and very profuse sulphide inclusions, resulting in an average sulphur
content of 0.6 % (Tab. 2). The abundance of shrinkage
porosity, together with the lack of any indication for
hot or cold working beyond the melting, reinforce the
initial interpretation of this sample as resulting from
metal spillage, probably during casting. As such, this
suggests that beads, or any other copper-based objects,
could have been manufactured locally at the site. The
identification of a cast bead on the same site strengthens
Sample
Code
S
Fe
Ni
Cu Zn As
Se
Sn
Pb
Bi
MK2
84.7
14.2
1.1
MK11
83.7
4.6 11.7
AE12
71.2
28.8
RYD1
12.4
87.6
RYD1
48.1
49.2
0.5
2.2
MYC4 20.4
79.6
MYC4
15.3 2.4 20.3
62.1
KAS1
84.4
11.7 3.9
GZ1
17.7
82.0
GZ1
13.9 0.9
85.3
LUA1 17.2
81.1
2.2
CHW1
8.3 5.4
86.3
MUH3
69.9
2.5 19.5 5.0
Tab 3. SEM-EDS results of the analyses of primary inclusions in the metal matrix. Elements in weight % and normalised to 100 %.
Journal of African Archaeology Vol. 7 (1), 2009
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Fig. 7. Unique pendant (BAR3) from the Zimbabwe
Tradition site of Baranda.
Fig. 8. Melted metal lumps from the
Zimbabwe Tradition site of Matanda
yaChiwawa.
Fig. 9. A unique octahedral bead (BRC1) from the
Zimbabwe Tradition site of Beryl Rose Claims.
88
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Mahonje Tradition materials (17th–19th century AD)
The majority of Mahonje Tradition beads, from three
sites in the middle Mazowe River basin, were small biconical beads made from a short triangular-section wire.
These metal beads were previously published as copper
beads (Pikirayi 1993: 157, 2003). However, ED-XRF
surface analyses showed that most of the specimens —
notably, including all of the bicone beads — were highzinc brasses (Tab. 1). SEM-EDS analyses confirmed zinc
contents above 33 wt% in all cases (33–41 %), together
with traces of lead (Tab. 2). The few Mahonje Tradition
beads not found to be brasses were some cylinder and
barrel specimens from Muchekayawa Hill. SEM-EDS
on one of them showed the presence of both tin and zinc
in levels of 3 % each (Tab. 2), which might constitute an
unintentional alloy resulting from scrap recycling.
Fig. 10. Biconical beads from the Zimbabwe Tradition site
of Great Zimbabwe attached on a fibre core.
Fig. 11. Cast bead (MYC1) from the Zimbabwe Tradition
site of Matanda yaChiwawa with a casting sprue still adhering on its surface.
Portuguese period materials (16th–17th century AD)
The site of Luanze has distinctive glazed wares, rectangular buildings of European style, and the absence of locally
made pottery, all of which suggest definite Portuguese
presence (Garlake 1967; Pikirayi 2001: 177). The beads
from Luanze were all barrel shaped and in a good state of
conservation. Initial ED-XRF chemical analyses of four
barrel beads from this site revealed that they were made
of pure copper. Only one bead from this site was subjected
to metallographic study, which revealed an annealed grain
structure, containing elongated sulphide inclusions.
Close stereoscopic inspection of the brass beads
revealed parallel longitudinal striations, clearly indicating that the wire was manufactured by drawing. Wire
drawing is a process whereby a cast or hammered rod of
metal is made longer and thinner by pulling it through
a hole in a ‘draw-plate’ (Ogden 1992: 46). The wire
drawing process is repeated through consecutively
smaller perforations until the wire is of the desired
gauge. In this case, the holes in the draw-plate would
have been triangular, to achieve the desired shape. It
is interesting to note that the mechanical properties of
brasses change quite dramatically in this compositional
range: with zinc contents in excess of 35 %, brasses
become much harder, and their percentage elongation
decreases (CDA 1962, 1963). Thus, the drawing of
these brass wires must have been quite labour intensive,
and probably required hot working, as reflected in their
microstructure (Fig. 12). It can thus be suggested that
a particular colour was sought with the alloy compositions, rather than a technically easier manufacture.
Discussion: metal sources, manufacturing
techniques and social values
The analytical study of beads from northern Zimbabwe
has revealed some insights upon which the questions outlined in the introduction can begin to be addressed. The
technical information embodied in these archaeological
artefacts reflects the context in which they were manufactured, traded and used. Not only can we identify the range
of metals and alloys available to different groups, and
changes over time, but also patterns in the selection and
use of metals and manufacturing techniques that might be
attributed to specific technological or cultural traditions.
This information is also important in suggesting possible
sources of raw materials and/or finished products.
Journal of African Archaeology Vol. 7 (1), 2009
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T.P. Thondhlana & M. Martinón-Torres
25 µm
Fig. 12. Section of biconical bead (CHW1), etched in ferric chloride solution, showing grains
Figure
12: Section
biconical
bead
(CHW1), etched
in ferric
showing
with
annealing
twinsof
and
inclusions.
Photomicrograph
under
planechloride
polarisedsolution,
light (500x).
grains with annealing twins and inclusions. Photomicrograph under plane polarised light
BeadWidth
compositions
(500x).
of the image 0.2 mm.
The compositional analyses allowed us to establish the
range of metals and alloys available to manufacturers
and consumers in northern Zimbabwe. Besides copper, at least three copper alloys were utilised, namely
tin bronze, arsenical copper and brass. A ternary alloy
of copper, zinc and tin was also represented by one
specimen (MUH3) from the seventeenth to nineteenth
century site of Muchekayawa Hill. Although the sample
is still small, it is worth highlighting some trends that
may be further questioned in future studies. The following discussion on bead compositions is based on
the data reported in Tables 1 and 2, and summarised
graphically in Figures 13 and 14.
Copper and tin bronze appear as the metals most
frequently used for beads during the first half of the
second millennium AD (Fig. 13). Noteworthy is the occurrence of two high tin bronze beads in Early Farming
Community (first millennium AD) contexts at Mabveni
and Little Over. According to current knowledge, tin
bronzes were not used in southern Africa before 1000
AD (Miller et al. 1995: 44). The possibility that these
beads represent an intrusion into earlier Gokomere
Tradition contexts is therefore highly plausible. Indeed
such an argument was presented for European glass
beads that post date 1836, found in association with
Gokomere pottery at the same site of Mabveni (Wood
2000: 78).
90
The earliest securely dated tin bronze beads from
northern Zimbabwe in this study were excavated at
Monk’s Kop (Mbagazewa) a site dating between the
twelfth and fourteenth century AD (Crawford 1967).
Tin bronzes are also present in the roughly contemporary (although possibly later) Harare Tradition burial
at Arlington Estate, although the majority of the beads
here appeared to have been made of copper. The binary
alloy appears again as the prevalent metal in Zimbabwe
Tradition sites, dated to the third quarter of the second
millennium AD.
The appearance of tin bronzes during the first
half of the second millennium AD, although not exceptional, raises some critical issues. Archaeomining
and archaeometallurgical studies have established that
indigenous miners and metalworkers produced copper
at least from the second half of the first millennium
AD in southern Africa (Summers 1969; Swan 2002).
Tin bronze metallurgy, however, presents some major
problems because the history of tin mining before
the middle second millennium AD in the region still
remains obscure (Chirikure et al. 2007). The only
unequivocal source of tin during the pre-colonial period in southern Africa is Rooiberg, in South Africa,
where an estimated 18,000 tonnes of ore had been
mined in preindustrial times (Grant 1990). Available
calibrated radiocarbon and AMS dates of tin mining
and smelting operations at Rooiberg are AD 1426–
1633 (Grn-5138) and AD 1436–1648 (ETH-5127)
Journal of African Archaeology Vol. 7 (1), 2009
Cultural
Affiliation
Mabveni
Gokomere
Mabveni
Gokomere
Monks Kop Musengezi
Object
MAB 1
MAB2
MK1
100,0
88,2
93,1
11,8
6,2
0,7
Monks Kop Musengezi
100%
Monks Kop Musengezi
95%
MK2
93,1
6,2
0,7
MK3
94,0
5,3
0,7
Monks Kop Musengezi
90%
MK11
94,9
5,1
Monks Kop 85%
Musengezi
MK27
90,0
9,2
Chemicalcomposition(wt%)
Site
Cu
Sn
Zn
As
Fe
Pb
S
Small Size, High Value
0,9
Beryl Rose Zimbabwe
Claims
88,3
MUH4
MUH3
CHE1
CHW2
LUA1
CHW1
KAS1
BRC1
GZ1
RYD1
MUY1
AE13
AE12
AE11
AE1
MK29
MK28
MK27
MK11
MK3
MK2
MK1
MAB2
BRC5
KAS1
Kasekete
Zimbabwe
Mahonje
Luanze
Portuguese LUA1
Chenguruv Mahonje
CHW1
e Hill West
Cultural affiliation
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MAB1
MK28
98,2
1,8
As
75%
Monks Kop Musengezi MK29
90,7
8,7
0,6
Zn
70%
Sn
Arlington Harare
AE1
100,0
65%
Estate
Cu
Cultural affiliation
Unalloyed copper
Arsenical copper Bronze
Brass
Arlington Harare
AE11
92,7
7,3
Musengezi
1
7
60%
Estate
Harare
7
1
Arlington 55%
Harare
AE12
100,0
Ingombe Ilede
3
Estate
Zimbabwe
6
16
Arlington 50%
Harare
AE13
100,0
Portuguese
4
Estate
Mahonje
1
13
Muyove
Ingombe
MUY1
97,5
2,5
Ingombe
RYD1
98,5
1,5
Rydings
Beadcodes
Zimbabwe GZ1
98,7
1,4
Great
Zimbabwe
Beryl
Rose
77,8(in wt%20,7
1,4 analysed
Fig.
13.Zimbabwe
Elemental BRC1
concentrations
and normalised) of the samples
Claims
BRC5
Monks Kop 80%
Musengezi
with SEM-EDS.
11,2
100,0
100,0
63,1
36,5
66,9
33,1
63,4
36,6
0,4
Portuguese
Chenguruv Mahonje
e Hill West
CHW2
Zimbabwe
Chenguruv Mahonje
e Hill East
CHE1
MuchekayaIngombe
Mahonje Ilede
MUH3
wa Hill
Muchekaya Mahonje
MUH4
wa Hill
94,2
2,9
58,7
3,0
41,3
Harare
Musengezi
0%
20%
40%
60%
Percentage of beads
Unalloyed copper
Arsenical copper
respectively (Grant 1994), which are slightly later
than the introduction of tin bronzes in southern Africa
and indeed at Monk’s Kop. Other sources of tin in
pre-colonial southern Africa have been suggested,
including Rusape and Masvingo, in the south-eastern
part of Zimbabwe (Prendergast 1979; Swan 1994:
28, 1996), but the archaeological evidence for these
is inconclusive (Chirikure et al. 2007). Against this
background, it is not possible to make any firm suggestion as to the potential origins of the tin present in
the Zimbabwean bronze beads. It is worth mentioning,
however, that a good number of the bronze beads analysed by SEM-EDS showed traces of iron, which were
not identified in the pure copper or brass samples (Tab.
80%
Bronze
100%
Brass
Fig. 14. Trends of metal and alloys use against cultural affiliation in northern Zimbabwe.
2). This might imply that iron was added as an impurity
with the tin. Previous analyses of Rooiberg tin ingots
have shown significant amounts of iron (Killick 1991;
Grant 1994; Miller et al. 1995: 43), and hence a link
between the two is plausible. Only further analytical
work, ideally involving lead isotope analyses, will be
able to ascertain this point.
Another aspect deserving attention is the apparently
different patterns of impurities detected in the bronze
beads found in Zimbabwe tradition sites when compared
to those of Gokomere and Harare Tradition sites. As
noted above, Zimbabwe Tradition beads show generally
stronger signatures of nickel, arsenic, silver and lead.
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Given the qualitative nature of our XRF data (which
discouraged us from presenting numerical values in Tab.
1), these observations should only be taken as strands
for further enquiry. Should these dissimilarities be confirmed, they would be indicative of different sources
of copper and/or tin, or at least suggestive of different
technological processes resulting in distinctive chemical
signatures. The best known copper mine in the region,
exploited during the second millennium AD, is that of
Copper Queen, located within the area of influence of
Ingombe Ilede groups (Swan 2002). However, no data
are available regarding the mineralogy and composition
of these ores, nor is there any definitive archaeological
evidence of copper smelting in the area.
Turning to arsenical copper beads, these artefacts were confined to the Ingombe Ilede Tradition
sites found to the west of northern Zimbabwe, and
it seems that arsenical copper was not widely used
in our study area. Intentional production of arsenic
usually requires advanced production processes, owing to the fact that arsenic is a volatile metal and an
attempt to smelt it from its ore will normally produce
just gas (Craddock 1995: 284). Moderately arsenicrich coppers, however, could be produced more easily
by the direct co-smelting of copper and arsenic ores
(Lechtman & Klein 1999), and this is probably the
case here. Occasional occurrences of arsenical coppers
have been encountered in Later Farming Community
period contexts in southern Africa. They include two
arsenical copper ingots from Rooiberg, dated to the
eleventh and thirteenth centuries AD, containing arsenic ranging from 14 % to 19 % (Grant et al. 1994:
90). Such high arsenic levels would make the metal
unworkable, and indeed it has been suggested that
these ingots were produced from the erroneous addition of annabergite, a hydrated nickel arsenate similar
in colour to copper ore, to a copper smelt (Friede
1975: 185). Thus arsenic-rich ores were plausibly
exploited in Rooiberg, but it is also possible that they
were available further North, in northwest Zimbabwe.
If one subscribes to the idea that Ingombe Ilede groups
sourced and distributed copper metal to their eastern neighbours (Pwiti 1991; Burrett 1998; Pikirayi
2001), it is intriguing that the only arsenical copper
beads documented in northern Zimbabwe come precisely from the Ingombe Ilede area. In view of the
overall scarcity of beads in these sites, and the fact
that they are made of a different metal, it is tempting
to think that Ingombe Ilede groups held a somewhat
different value system, where beads were a lesser
important component even as burial goods.
the southern site of Great Zimbabwe, as this would
appear to strengthen the suspected links between Ingombe Ilede and Great Zimbabwe (Walsh 1997). In
contrast, the Zimbabwe Tradition sites in the North
yielded only copper and bronze beads. Thus, although
Zimbabwe Tradition communities maintained customs
such as building and pottery styles, the beads indicate
an adaptation to the potentially different availability of
metals in the North. At the Portuguese period site of
Luanze, pure copper seems to have prevailed. This is
a rather interesting point, as one would have expected
to find an assortment of exotic copper alloy metals
since this was a Portuguese settlement.
Lastly, brass metal beads were confined to the
later Mahonje Tradition sites. Brassmaking technology
presented practical challenges to pre-modern metal
workers in many regions. Zinc is an extremely volatile
metal, which explains why it was a relatively late comer in the history of metallurgy. Before the inception of
zinc distillation, brass was made by a process known
as cementation, which involved the heating of metallic
copper with zinc ore and charcoal in a closed crucible,
thus making the alloy directly (Martinón-Torres &
Rehren 2002; Craddock & Eckstein 2003; Rehren &
Martinón-Torres 2008). However, the maximum zinc
content achievable in cementation brasses is between
28 % and 33 % (Newbury et al. 2005), that is below
the zinc levels in the Mahonje beads (33–41 %). Furthermore, cementation brasses generally contain small
levels of iron (Craddock 1985: 26), which were not
detected in these objects.
Based on historical evidence, the exploitation
of zinc ores in sub-Saharan Africa was unknown before the nineteenth century; hence brasses in early
archaeological contexts in southern Africa can only
be explained in relation to contacts with other regions
(Herbert 1984: 97; Bisson 1997: 130). On the basis of
both technological and historical facts, the plausible
source of brass metal in the later Mahonje sites is India, a region where zinc was produced by distillation
since the early second millennium AD (Craddock
et al. 1998). Contact between southern Africa and
India was long established even before the coming of
the Portuguese to the region. Evidence of imported
brass is also consistent with glass beads of Asian
origin recovered from the same Mahonje Tradition
sites (Pikirayi 1993, 2003). Elsewhere in the region,
brass beads with similar zinc contents were found in
early second millennium AD deposits at the sites of
Phalaborwa, Parma and Mapungubwe in South Africa
(Miller 2001, 2002: 1127).
It is also interesting to point out that the only
other arsenical copper beads identified come from
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Manufacturing techniques
The manufacturing techniques used in the crafting of
these beads also help us address issues of source and
technological innovations. It was established that most of
these artefacts were manufactured by a relatively simple
repertoire of techniques, typically involving the use of
short rods of wire that were folded into a circular shape,
typically with a final annealing stage. Only mechanical
joins in the form of overlapping seams, carefully treated
from the outside, were noted on some beads. Importantly,
without metallographic analyses, those beads could have
been misidentified as cast forms. Both metallographic
and compositional analyses of the seams revealed that
soldering, i.e. the joining of metals with an alloy of lower
melting temperature, was not employed. The absence of
the soldering technique has also been noted for second
millennium AD gold articles in southern Africa (Oddy
1984, 1991), which led Oddy (1984) to conclude that
the artefacts were crafted by indigenous Africans. The
same argument may be extended for these copper-based
metal beads from northern Zimbabwe. The fabrication
methods employed in the production of these artefacts
seem consistent with our knowledge of the technology
of the second millennium AD (Miller & van der Merwe
1994; Miller 1996, 2001). The same cold working and
annealing techniques were used by indigenous metalworkers from the Tsodilo area in Botswana from the first
millennium AD (Miller 1996).
proposes that it was introduced by contacts along the
east coast. The absence of wire drawing knowledge
in Central Africa, an area with a long history of metal
production, cements the argument for foreign influence
(Bisson 2000: 105). Although it would be possible for
the Mahonje beads to have been imported in their final
shape, it is more likely that indigenous metalworkers
manufactured the beads from imported metal. This assertion is supported by seventeenth-century and later
historical accounts recording such a practice (Ellert
1993: 109–110; Maggs & Miller 1995; Miller 2002:
1127); but also by the fact that the peculiar bead shape
seems adapted to the African style.
Although their recovery was low, cast forms were
also recorded in our sample. Only three beads were
positively identified as cast forms after stereomicroscopic analysis, all of them from Zimbabwe Tradition
sites. There is a possibility that for the more complex
forms like the octahedrals, the lost-wax technique was
employed, but these beads were possibly not manufactured in it the region since such technical sophistication
was absent outside West Africa during the pre-colonial
period (Herbert 1984: 87). However, the fact that one
unfinished cast bead was found at Matanda yaChiwawa,
where melted metal lumps were found too, is strongly
suggestive of indigenous workmanship.
Consumption and value
Beads with identical shapes, however, were manufactured using different techniques, and thus subtle
“technological choices” may indicate a diversity of
technological traditions. Noteworthy here are the triangular-section metal wires used to produce biconical
beads. These wires were either hammered into shape,
as represented in the bicones from Arlington and Great
Zimbabwe, or they were drawn through a plate, as was
the case with the Mahonje Tradition beads. In this regard, the technological studies add another dimension
to typological analyses based on shape.
The presence of wire-drawn biconical beads with
longitudinal surface striations deserves further comment. The chronological development of the wire
drawing technique has been studied by historians of
technology. The technique appears in the early Middle
Ages in Europe (Oddy 1991: 193). In southern Africa,
wire drawing devices like drawing plates and tongs
were excavated at several archaeological sites dating to
the fourteenth century AD (Fagan et al. 1969: 92–93).
Oddy (1991: 194) suggests that wire drawing was an
independent invention in Africa, whilst Bisson (2000:
105) highlights the confinement of the technique to
eastern, east-central and southern Africa, and therefore
After a metal is won from an ore, it is given social roles
that may change during its lifetime (Childs & Killick
1993: 330). The social roles and values of different
metals are largely dependent on their physical properties, including aspects such as hardness and corrosion
resistance but also sensorial dimensions such as colour
or smell. The value of different metals is thus conditioned by physical factors but also culturally constructed (Jones 2004), resulting in a variety of economic and
symbolic values given to specific metals and object
forms by different societies. Paradigmatic examples
of the culture-specific value of metals are provided by
various historical societies in different regions that,
unlike Europeans, esteemed brass much more highly
than gold (Miller & Markell 1993; Garenne-Marot
& Mille 2007; Martinón-Torres et al. 2007).
The overall significance of copper and its alloys to
traditional African institutions has been firmly established
(Herbert 1984, 1996) but the internal diversity of the
values of different metals within southern African communities is more difficult to reconstruct. As stated by
Caple (2006: 9), the context in which the objects appear
in the archaeological record invariably helps define their
Journal of African Archaeology Vol. 7 (1), 2009
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T.P. Thondhlana & M. Martinón-Torres
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meaning, and unfortunately the contexts for the beads
analysed here are not well understood in all cases. There
is no doubt that copper and bronze were used as prestige
commodities in northern Zimbabwe, as supported by the
evidence of the beads deposited in burials associated with
the elite at Arlington Estate and Monk’s Kop. At Ingombe
Tradition sites, however, although the importance of copper is widely attested in the form of ingots, the archaeological evidence suggests that beads did not play such an
important role in personal or funerary contexts.
While no overall correlations were found between
bead types and metal composition across the different
sites, there is a prominent trend in the fact that certain
alloys are apparently constrained to specific sites, and
vice versa (Fig. 14). Although this could simply be a
bias of our relatively small sample size, it may also be
an indication of the different accessibility of different
groups to certain metals, or perhaps a diversity of cultural appreciations.
Another very significant pattern across all of the
beads analysed is the lack of ternary alloys, with only
one exception to this out of approximately fifty objects. Ternary or quaternary copper alloys containing
combinations of arsenic, tin and/or zinc are often taken
as indicative of haphazard recycling, where different
copper alloys are melted together in order to be recast
into new objects. The well-defined compositions of
these beads denote that they were not normally a part
of a metal recycling system, not even when they were
not deposited in burials. This further highlights the
important cultural value they may have held, beyond
their economic value as metals.
Finally, some of the metal articles are a clear testimony of trade and as such allow us to interpret the
changing trading relations in northern Zimbabwe during the second millennium AD. Copper-based metal
articles were excavated in areas which are unlikely
to have produced them due to lack of copper ores and
production evidence. The predominance of brass beads
from the seventeenth century can be explained with
reference to the coast-interior trade, initiated by the
Swahili merchants and later by the Portuguese in the
last half of the second millennium AD (Pikirayi 2003).
This, however, is not meant to claim that these beads
were used as a currency. Whereas the value of copper
ingots in the form of manilas (West Africa), H-shaped,
flanged and handa type ingots (Central Africa) as general purpose currency has been established beyond any
reasonable doubt (Bisson 1975, 2000), these beads are
unlikely to have functioned as a form of general purpose currency, due to their size variability and overall
lack of standardisation (Bisson 1975).
94
Conclusion and future prospects
This preliminary analytical study of copper based
metal articles from northern Zimbabwe showed that
four different alloys were employed. Stereomicroscopic and metallographic analyses revealed a range
of manufacturing methods that, in general, do not
suggest foreign influence, and as such credit should
be given to indigenous African metal workers. The
compositional results indicate that there was a shift
from the use of copper and bronze to high zinc brasses
through time. Overall, these data conform well to the
socio-economic and political dynamics of the second
millennium AD in northern Zimbabwe. However, future work should focus on the internal diversity noted
to assess the extent to which environmental, political
or cultural factors conditioned the different trends
observed across the sites.
Lacking reliable contextual information and a
larger data set, it is difficult to determine the socioideological role of copper and its alloys, beyond general assertions of their important cultural significance.
This problem will only be overcome if archaeologists
recognise the importance of metals and their related
debris as a critical part of the Farming Communities
archaeological record. Future archaeometallurgical
research in northern Zimbabwe should be complemented with geological information, namely through
archaeologically informed geochemical and isotopic
surveys of the possible ore sources, which should
allow a more systematic insight into the patterns of
trade and consumption of metals. Besides artefacts,
the analysis of metal production debris from archaeological sites in Zimbabwe should receive the academic
attention that it deserves. Although investigations of
metal artefacts provide important information, complementary data can be gained with the analysis of
production remains. Long-term, systematic archaeometallurgical projects should be carried out in areas
associated with ancient copper mining to establish
smelting production, such as the north-western part of
Zimbabwe, whilst extant museum assemblages continue to be analysed. However, this is not to say that
archaeometallurgical research should be constrained
to Zimbabwe. In the second millennium AD, the Zimbabwe plateau was part of successive world systems
connected with Islamic and Christian cultures, and
also linked by long distance trade of metals to far
away areas within the African continent. Thus, only
integrated approaches will allow a sound understanding of the cultural and technological dimensions of
pre-colonial African metals.
Journal of African Archaeology Vol. 7 (1), 2009
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Acknowledgements
An earlier version of this work was submitted in partial
fulfilment of the requirements of an MSc dissertation in
Technology and Analysis of Archaeological Materials at
the Institute of Archaeology, University College London
(Thondhlana 2007). Financial support was made available from the European Union, through a fellowship
under the Marie Curie Early Stage Research Training
Programme (contract MEST-CT-2004-514509) to one of
the authors (TPT). We are indebted to the late Professor
Peter Ucko for his unreserved support of African indigenous archaeology, and to Professors Thilo Rehren and
Gilbert Pwiti for their precious advice. Previous drafts
of this paper were read and commented upon by Dr
Shadreck Chirikure, Dr Simon Hall, Dr Robert Soper,
Rob Burrett and Paul Hubbard and we would like to
thank them for their important suggestions. We would
also like to thank the National Museums and Monuments of Zimbabwe (NMMZ) which gave us temporary
export permits and also allowed us to carry out invasive
sampling on some of their collections. The technical
assistance provided by Kevin Reeves, Philip Connolly
and Simon Groom at the UCL Institute of Archaeology
is also gratefully acknowledged. We are also grateful to
Professors E.W. Herbert and D. Killick and the editors
of this journal who suggested valuable changes to our
earlier draft. However, the errors and omissions in this
paper remain our sole responsibility.
Copper Development Association (CDA), 1963. Brasses and
Other Copper-Zinc Alloys. CDA Publication 6, London. (2nd
rev. edn.; 1st edn. 1935.)
Childs, S.T. 1991. Transformations: iron and copper production
in Central Africa. In: Glumac, P.D. (ed.), Recent Trends in
Archaeometallurgical Research. MASCA Research Papers
in Science and Archaeology. The University Museum of
Archaeology and Anthropology University of Pennsylvania,
Philadelphia, pp. 33–46.
Childs, S.T. & Killick, D. 1993. Indigenous African metallurgy: nature and culture. Annual Review of Anthropology
22, 317–337.
Childs, S.T. & Dewey, W.J. 1996. Forging symbolic meaning in
Zaire and Zimbabwe. In: Schmidt, P.R. (ed.), The Culture and
Technology of African Iron Production. University Press of
Florida, Gainesville, pp. 145–171.
Chirikure, S. 2006. New light on the Njanja iron working:
towards a systematic encounter between ethnohistory and
archaeometallurgy. South African Archaeological Bulletin
61 (184), 142–151.
Chirikure, S., Hall, S. & Miller, D. 2007. One hundred years on:
what do we know about tin and bronze production in southern
Africa? In: La Niece, S., Hook, D. & Craddock, P. (eds.),
Metals and Mines: Studies in Archaeometallurgy. Archetype
Publications, London, pp. 112–119.
Chirikure, S. & Rehren, Th. 2004. Ores, slags and furnaces:
aspects of iron working in the Nyanga Complex. African
Archaeological Review 21 (3), 135–152.
Chirikure, S. & Rehren, Th. 2006. Iron smelting in precolonial
Zimbabwe: evidence for diachronic change from Swart village and Baranda, Northern Zimbabwe. Journal of African
Archaeology 4 (1), 37–54.
References
Bailey, A.R. 1982. The Role of Microstructure in Metals: An
Introductory Volume. The Gatwick Press Ltd, Sussex.
Bisson, M.S. 1975. Copper currency in central Africa: the archaeological evidence. World Archaeology 6 (3), 276–292.
Bisson, M.S. 1997. Copper metallurgy. In: Vogel, J.O. (ed.),
Encyclopaedia of Pre-colonial Africa: Archaeology, History,
Languages, Cultures and Environments. Altamira Press,
California, pp. 125–132.
Bisson, M.S. 2000. Pre-colonial copper metallurgy: sociopolitical
context. In: Bisson, M.S., Childs, S.T., de Barros, P. & Holl,
A.F.C. (eds.), Ancient African Metallurgy: The Socio-Cultural
Context. Altamira Press, Walnut Creek, pp. 83–145.
Burrett, R.S. 1998. Shadows of Our Ancestors: Some Preliminary Notes on the Archaeology of Zimbabwe. Texel Desktop
Publishing, Harare.
Caple, C. 2006. Objects: Reluctant Witnesses to the Past.
Routledge, London.
Copper Development Association (CDA), 1962. Copper and
Copper Alloys: Compositions and Mechanical Properties.
CDA Publication 36, London. (12th rev. edn.)
Craddock, P.T. 1985. Medieval copper alloy production and
West African bronze analyses - Part 1. Archaeometry 27
(1), 17–41.
Craddock, P.T. 1995. Early Metal Mining and Production. Edinburgh University Press, Edinburgh.
Craddock, P.T. & Eckstein, K. 2003. Production of brass in
antiquity by direct reduction. In: Craddock, P.T. & Lang,
J. (eds.), Mining and Metal Production Through the Ages.
British Museum Press, London, pp. 216–230.
Craddock, P.T., Freestone, I.C., Gurjar, L.K., Middleton, A.P. &
Willies, L. 1998. Zinc in India. In: Craddock, P.T. (ed.), 2000
Years of Zinc and Brass. British Museum Occasional Paper
50. British Museum, London, pp. 27–72.
Crawford, J.R. 1967. The Monk’s Kop ossuary. Journal of African
History 8 (3), 373–382.
Ellert, H. 1993. Rivers of Gold. Mambo Press, Gweru.
Fagan, B.M., Phillipson, D.W. & Daniels, S.G.H. 1969. Iron Age
Cultures in Zambia: Dambwa, Ingombe Ilede and the Tonga.
Volume 2. Chatto and Windus, London.
Journal of African Archaeology Vol. 7 (1), 2009
95
T.P. Thondhlana & M. Martinón-Torres
Friede, H.M. 1975. Notes on the composition of pre-European
copper and copper-alloy artefacts from the Transvaal. Journal
of the South African Institute of Mining and Metallurgy 75,
185–191.
Garenne-Marot, L. & Mille, B. 2007. Copper-based metal in
the Inland Niger delta: metal and technology at the time of
the Empire of Mali. In: La Niece, S., Hook, D. & Craddock,
P. (eds.), Metals and Mines: Studies in Archaeometallurgy.
Archetype Publications, London, pp. 159–169.
Garlake, P. 1967. Seventeenth century Portuguese earth-works
in Rhodesia. South African Archaeological Bulletin 21 (84),
157–170.
Downloaded by University Arizona - Library on September 28 2010
Garlake, P. 1970. Iron Age sites in the Urungwe District of Rhodesia. South African Archaeological Bulletin 25 (97), 25–44.
Garlake, P. 1972. Excavations at the Nhunguza and Ruanga ruins
in northern Mashonaland. South African Archaeological Bulletin 27 (107&108), 107–143.
Grant, M.R. 1990. A radiocarbon date on a tin artifact from Rooiberg. South African Journal of Science 86 (2), 63.
Maggs, T. & Miller, D. 1995. Sandstone crucibles from Mhlopeni,
KwaZulu-Natal: evidence of precolonial brassworking. Natal
Museum Journal of Humanities 7, 1–16.
Martinón-Torres, M. & Rehren, Th. 2002. Agricola and Zwickau:
theory and practice of Renaissance brass production in SE
Germany. Historical Metallurgy 36 (2), 95–111.
Martinón-Torres, M., Valcárcel Rojas, R., Cooper, J. & Rehren, Th.
2007. Metals, microanalysis and meaning: a study of metal objects
excavated from the indigenous cemetery of El Chorro de Maíta,
Cuba. Journal of Archaeological Science 34 (4), 194–204.
Miller, D. 1992. Iron Age Metal Working at Tsodilo Hills Northwestern Botswana. Unpublished Ph.D. Thesis, University of
Cape Town, Cape Town.
Miller, D. 1996. The Tsodilo Jewellery: Metal Work from Northern
Botswana. UCT Press (Pty) Ltd, Cape Town.
Miller, D. 2001. Metal assemblages from Greefswald areas K2,
Mapungubwe Hill and Mapungubwe Southern Terrace. South
African Archaeological Bulletin 56 (173&174), 83–103.
Grant, M.R. 1994. Iron in ancient tin from Rooiberg, South Africa.
Journal of Archaeological Science 21 (4), 445–460.
Miller, D. 2002. Smelter and smith: iron Age metal fabrication
technology in southern Africa. Journal of Archaeological
Science 29 (10), 1083–1131.
Grant, M.R., Huffman, T.N. & Watterson, J.I.W. 1994. The
role of copper smelting in precolonial exploitation of the
Rooiberg tin field. South African Journal of Science 90
(2), 85–90.
Miller, D. 2003. Indigenous copper mining and smelting in precolonial southern Africa. In: Craddock, P. & Lang, J. (eds.),
Mining and Metal Production Through the Ages. The British
Museum Press, London, pp. 101–110.
Herbert, E.W. 1984. Red Gold of Africa: Copper in Precolonial History and Culture. University of Wisconsin Press,
Madison.
Miller, D. & Markell, A. 1993. Dutch brass buttons from the
Cape to the Marico. Southern African Field Archaeology 2
(2), 107–108.
Herbert, E.W. 1996. Metals and power at Great Zimbabwe. In:
Pwiti, G. & Soper, R. (eds.), Aspects of African Archaeology: Papers From the 10th Congress of the Pan African
Association for Prehistory and Related Studies. University
of Zimbabwe Publications, Harare, pp. 641–647.
Miller, D., Boeyens, J. & Küsel, M. 1995. Metallurgical analysis
of slags, ores and metal artefacts from archaeological sites in
North-West Province and Northern Transvaal. South African
Archaeological Bulletin 50 (161), 39–54.
Huffman, T.N. 1971. A guide to the Iron Age of Mashonaland.
Occasional Papers of National Museums and Monuments of
Rhodesia 4 (1), 20–44.
Miller, D. & van der Merwe, N.J. 1994. Early Iron Age metal
working at the Tsodilo Hills, northwestern Botswana. Journal
of Archaeological Science 21 (1), 101–115.
Huffman, T.N. 1974. The linguistic affinities of the Iron Age in
Rhodesia. Arnoldia 7 (7), 1–12.
Newbury, B.D., Notis, M.R. & Newbury, D.E. 2005. Revising
the zinc composition limit of cementation brass. Historical
Metallurgy 39 (2), 75–81.
Huffman, T.N. 1980. Corrected radiocarbon dates for the Iron Age
of Rhodesia. In: Beach, D.N. (ed.), The Shona and Zimbabwe
900–1850. Mambo Press, Gweru, pp. 321–325.
Oddy, A. 1984. Gold in the southern African Iron Age: a technological investigation of the Mapungubwe and other finds.
Gold Bulletin 17 (2), 70–78.
Jones, A. 2004. Archaeometry and materiality: materials based
analysis in theory and practice. Archaeometry 46 (3),
327–338.
Oddy, A. 1991. Gold foil, strip and wire in the Iron Age of southern
Africa. In: Scott, D. A., Podany, J. & Considine, B.B. (eds.), Ancient and Historic Metals Conservation and Scientific Research.
The Getty Conservation Institute, Los Angeles, pp. 183–196.
Killick, D. 1991. A tin lerale from the Southpansberg, northern
Transvaal, South Africa. South African Archaeological Bulletin 46 (154), 137–141.
Ogden, J. 1992. Interpreting the Past: Ancient Jewellery. British
Museum Press, London.
Lechtman, H. & Klein, S. 1999. The production of copper–arsenic
alloys (arsenic bronze) by cosmelting: modern experiment,
ancient practice. Journal of Archaeological Science 26 (5),
497–526.
Pikirayi, I. 1993. The Archaeological Identity of the Mutapa State:
Towards an Historical Archaeology of Northern Zimbabwe.
Studies in African Archaeology 6. Societas Archaeologica
Uppsaliensis, Uppsala.
96
Journal of African Archaeology Vol. 7 (1), 2009
Small Size, High Value
Downloaded by University Arizona - Library on September 28 2010
Pikirayi, I. 1996. Archaeological pointers of the decline or collapse of the Mutapa State. Zimbabwea 4, 9–22.
Summers, R. 1969. Ancient Mining in Rhodesia and Adjacent
Areas. Museum Memoir No. 3. The Trustees of the National
Museums of Rhodesia, Salisbury.
Pikirayi, I. 1998. The threatened cultural landscape: historical
period sites from northern Zimbabwe, AD 1500–present.
In: Chiwome, E.M. & Gambahaya, Z. (eds.), Culture and
Development: Perspectives from the South. Mond books,
Harare, pp. 85–92.
Swan, L. 1994. Early Gold Mining on the Zimbabwean Plateau:
Changing Patterns of Gold Production in the First and Second
Millennia AD. Studies in African Archaeology 9. Societas
Archaeologica Uppsaliensis, Uppsala.
Pikirayi, I. 2001. The Zimbabwe Culture: Origins and Decline of
Southern Zambezian States. Altamira Press, Walnut Creek.
Swan, L. 1996. The use of grinding hollows for ore milling in
early Zimbabwe metallurgy. Cookeia 1 (6), 71–92.
Pikirayi, I. 2003. Shifting patterns of trade in the western Indian
Ocean zone: Northern Zimbabwe, 1500–1750 AD. In: Chami,
F., Pwiti, G. & Radimilahy, C. (eds.), Climatic Change, Trade
and Modes of Production in Sub-Saharan Africa. Studies in
the African Past 2. Dar es Salaam University Press, Dar es
Salaam, pp. 129–154.
Swan, L. 2002. Excavations at Copper Queen Mine, northwestern Zimbabwe. South African Archaeological Bulletin 57
(176), 72–78.
Prendergast, M.D. 1979. Cornucopia: Phase 1 Zimbabwe stone
buildings associated with an Iron Age tin mine? Rhodesian
Prehistory 19, 1–13.
Thondhlana, T.P. 2005. Style, Space and Time: A Critical Analysis
of the Chronology and Spatial Distribution of Copper and
Copper Alloy Beads from Zimbabwean Iron Age Sites. Unpublished B.A. Honours Dissertation, History Department,
Archaeology Unit, University of Zimbabwe, Harare.
Pwiti, G. 1991. Trade and economies in southern Africa: the
archaeological evidence. Zambezia 18 (2), 119–129.
Pwiti, G. 1996. Continuity and Change: An Archaeological
Study of Farming Communities in Northern Zimbabwe AD
500–1700. Studies in African Archaeology 13. Archaeologica
Uppsaliensis, Uppsala.
Rehren, Th. & Martinón-Torres, M. 2008. Naturam ars imitata.
European brassmaking between craft and science. In: Martinón-Torres, M. & Rehren, Th. (eds.), Archaeology, History
and Science: Integrating Approaches to Ancient Materials.
UCL Institute of Archaeology Publications. Left Coast Press,
Walnut Creek, pp. 167–188.
Robinson, K.R. 1959. Khami Ruins. Cambridge University Press,
Cambridge.
Scott, D. 1991. Metallography and Microstructure of Ancient and
Historic Metals. J. Paul Getty Trust, Los Angeles.
Soper, R. 2002. Nyanga: Ancient Fields, Settlements and Agricultural History in Zimbabwe. The British Institute in Eastern
Africa, London.
Swan, L. 2007. Economic and ideological roles of copper ingots
in prehistoric Zimbabwe. Antiquity 81 (314), 999–1012.
Thondhlana, T.P. 2007. An Investigation of Fabrication Technology and Composition of Copper and Copper Alloy Beads from
Second Millennium AD Archaeological Sites in Northern
Zimbabwe. Unpublished MSc Dissertation, Institute of Archaeology, University College London, London.
Tilley, C. 2006. Objectification. In: Tilley, C., Keane, W., Küchler,
S., Rowlands, M. & Spyer, P. (eds.), Handbook of Material
Culture. Sage Publications, London, pp. 60–73.
Tilley, C., Keane, W., Küchler, S., Rowlands, M. & Spyer, P. 2006.
Introduction. In: Tilley, C., Keane, W., Küchler, S., Rowlands,
M. & Spyer, P. (eds.), Handbook of Material Culture. Sage
Publications, London, pp. 1–6.
Walsh, K.L. 1997. Metals, minerals and rocks in the Great Zimbabwe State. The Zimbabwe Science News 31 (1), 5–11.
Wood, M. 2000. Making connections: relationships between
international trade and glass beads from the Shashe-Limpopo
area. South Africa Archaeological Society Goodwin Series
8, 78–90.
Soper, R. & Pwiti, G. 1988. Preliminary report on excavations
at Wazi Hill, Centenary. Zimbabwean Prehistory 20, 16–20.
Journal of African Archaeology Vol. 7 (1), 2009
97