Analysis of Glass Beads and Glass Recovered from an Early 17th

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Chapter 8

Analysis of Glass Beads and Glass Recovered from an Early 17th-century Glassmaking House in Amsterdam 4

K . Karklins1, R. G . V . Hancock2, J. Baart3 , M.L. Sempowski , J . - F . Moreau , D . Barham , S. Aufreiter , and I. Kenyon 5

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Parks Canada, Ontario Service Centre, Ottawa, O N K1A 0M5, Canada SLOWPOKE-2 Facility, Department of Chemistry and Chemical Engineering, Royal Military College, Kingston, ON K 7 K 7B4, Canada Archaeologie, Stedelijk Beheer, Amsterdam, Netherlands Rochester Museum and Science Center, Rochester, NY 14603 Laboratoire d'Archéologie et Département des Sciences Humaines, Université du Québec à Chicoutimi, Chicoutimi, PQ G7H 2B1, Canada Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, O N M5S 3E5, Canada Ontario Heritage Foundation, Toronto, ON M5C 1J3, Canada 2

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A variegated sample of two hundred and ninety glass beads and glass fragments recovered from the wasters of a glassmaking house in Amsterdam have been analysed by instrumental neutron activation analysis to determine their bulk elemental compositions. Since the archaeological context reveals that the material was deposited between 1601 and 1610, the recovered data provide a chronological anchor for beads of the same

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© 2002 American Chemical Society

Jakes; Archaeological Chemistry ACS Symposium Series; American Chemical Society: Washington, DC, 2002.

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chemistry on archaeological sites in North America. Hence, knowledge of these Dutch bead chemistries is significant not only in determining the source of glass trade beads found in North America, and perhaps elsewhere in the world, but also in establishing the temporal locus of early archaeological sites with limited European artifacts save glass beads.

Since glass trade beads have been recovered from many aboriginal, contact and post-contact sites in northeastern North America, there has been a long-term interest amongst archaeologists to classify, date, and interpret them. The earliest classification system was based on form (1) but this was not found to be practicable by later researchers. Consequently, in 1970, Kidd and Kidd (2) published their taxonomic system for glass beads which segregated specimens on the basis of manufacture, followed by shape, diaphaneity, colour, and size. Their system was later significantly expanded by Karklins (3). The first reported chemical analyses of glass beads (4% using energy dispersive x-ray fluorescence analysis (EDXRF), showed that drawn glass beads were made from soda-rich glasses while wound beads were made from potash-rich glasses. Subsequent studies, using non-destructive instrumental neutron activation analysis (INAA), have been conducted on blue glass beads from northeastern North America (5, 6, 7, 8, 9% and white glass trade beads from northeastern North America (10, 11, 12). These studies have shown that the major and trace element chemistries of glass beads may be used to sort similar looking beads into chemical groups, using their elemental concentration fingerprints. These elemental fingerprints have proven to been useful in both distribution studies and in chronological studies of glass trade beads. In many cases, from historic records (e.g. 13% it has been possible to link nonspecific traders (French, Dutch, and English) with beads found in different geographical regions. Although we tend to assume the opposite, there is no direct link between the nationality of the trader and the source country, or city, of the articles traded. The determination of the nation, city, or, most optimistically, specific glass beadmaking house(s) that made the beads traded into North America is the next major step in elucidating the nature of a small part the Europe-North America trading system. So, a small step in this direction comes from the analysis of glass beads and glass fragments excavated from the wasters of a specific glassmaking house in Amsterdam that was in operation from 1601 to 1610. This type of study allows us to generate both the chronological beginning and the


112 potential production source of specific chemistries of glass beads that were traded to North America, and indeed, starting in the 1620s, around the world.


Site Rescue excavations at two contiguous sites (Asd/Kg9 and K g 10) on the Keizersgracht canal between Wolvenstraat and Hartenstraat in downtown Amsterdam uncovered extensive glass- and beadmaking waster deposits (14). The larger of the two sites (Asd/KglO) was uncovered in 1981 by the municipal Department of Public Works while installing a sewer line along the east side of the canal. Glassmaking debris was found to cover a region at least seventy metres long. Recovered by carefully washing and sorting the fill, the beads and beadmaking refuse were found to be concentrated in an area about two metres across and at a depth of four metres below street level. Over 50,000 specimens were recovered, including finished beads, malformed rejects, and tube fragments, all of drawn manufacture. The deposit also contained chunks of vari-coloured glass, numerous coloured glass rods, crucible remnants, and a variety of drinkingglass fragments, all indicating that this was material from a local glasshouse. The archaeological context, as well as the associated ceramics and glassware, reveals that the glasshouse operated between 1601 and 1610.

Experimental Methods Two hundred and ninety drawn glass beads and fragments of varying colour, structure (flashed, cored and uncored), sizes, and shapes from site Asd/KglO were analyzed non-destructively using instrumental neutron activation analysis at the S L O W P O K E Reactor Facility of the University of Toronto. These beads had to be neutron-irradiated as little as possible in order to minimize the build-up of radioactivity from Sb (half-life 2.75 days) and from Sb (half-life 60.9 days) in the Sb-rich beads, so that they could be returned to their owners within a reasonable amount of time. Beads of mass 5-10 mg were first cleaned ultrasonically, as required. They were stored individually in 1.2 mL polyethylene vials, were irradiated serially for five minutes at a neutron flux of 1.0 * 10 neutrons.cm" .sec . Five to seven minutes after irradiation, the induced radioactivity was counted for five minutes using a hyper-pure germanium detector-based gamma-ray spectrometer. This produced analytical concentration data for cobalt (Co), tin (Sn), copper (Cu), sodium (Na), aluminium (Al), manganese (Mn), chlorine (CI) and calcium (Ca). The samples were recounted for five to thirty-three minutes the next day to measure the concentrations of the longer-lived radioisotopes of Na, arsenic (As), 122

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antimony (Sb) and potassium (K). The Na measurements were used to link both counts. Elemental concentrations were calculated using the comparator method, based on elemental standards. Beads of larger masses were irradiated at suitably lower neutron fluxes to make just enough radioactivity for reasonable chemical analyses.

Results and Discussion The colours of the analyzed glasses were turquoise blue (14 samples), royal blue (12 samples), white (45 samples), red (135 samples), black (52 samples), colourless (21 samples) and gold (11 samples). Table I lists the samples by colour, shape, and form. The gold coloured beads were made from leaded glasses. A l l of the other samples were soda-lime-silica glasses, with variable amounts of potash. The complete data set is available from the authors.

Turquoise Blue Glasses Twelve round turquoise blue beads (Table II; samples 1-12) are characterised by high N a (11.5 % to 13.0 %) and high CI (1.49 to 2.01 ), and low K (1.7 % to 2.8 %), low Ca (3.3 % to 5.4 %), and low A l (0.48 % to 0.64 %). In terms of the gross glass chemistry, these beads are chemically similar to Ontario Bead Period II («1600-1620) and Bead Period III («1620-1650) turquoise blue beads, as reported in Hancock et al 1994. The two scrap samples (283 and 288) are Sn-rich glasses of different basic chemistries. Scrap 283 has a curious K-rich/Na-rich composition, which is close to the chemistry of colourless scrap 263 (see Table III) and which may perhaps be related to enamel work.

Royal Blue Glasses Twelve royal blue (the Kidds' "brite navy") beads (Table II, samples 73-84) were all lime-rich (5.6 to 7.6 % Ca) soda glasses, coloured with Co, with about 2-3 times as much As, as was observed by Hancock et al 2000. Relative to the turquoise blue beads, these cobalt blue beads are lower in N a and CI and higher in Ca, A l , and much higher in M n . Either the extra M n was added intentionally or it came into the glass with the Co-colouring material. Ten of the twelve beads (samples 73-82) are chemically consistent, forming a single chemical group, while beads 83 and 84 are each quite different.


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Table I. Summary Data

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Colour turquoise blue-green royal blue white

1-12 283,288 73-84 13-24 25 193-196 245-256

redwood

black

colourless

gold

258, 260-263,268 275-277 281-290 26-37 51-62 85-101 102-114 115-127 133-151 152 153-172 173-192 237-244 39-50 197-216 217-236 128-132 257-270 271-280 287 38 63-72

Description Round Fragments Round clear light grey/op white/cl light grey opaque white fragment tubular fragments thin red and blue striped tube frags flat sheet fragments bead fragments fragments (less 283,287,288) round/circular grey/green cored circular (cc) red solid tubes (tu) black cored tubes tubes flashed in clear glass cored barrels/circulars cored circular cored round/circular cored circular/round broad blue + white stripes Round round black/grey circular black/grey Wasters cullet - flat sheets lumps and chunks Fragment opaque light light tubes

Kidd Sc

Kidd ID Hal IIa55 IVall

Ib7

IIal/IIa2 IVa2 Ial(a) Illal Ial(b) IIal/IIa2 IIa2 IVa2/IVa3 IVa5/IVa6 IIa6 IIa6 IIa7

IIal7 Ia7


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Table II. Data for the Blue Glasses


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Al

Ca

CI

Co

Cu

Na

%

% ppm

%

Mn ppm

K

%

%

%

0.79 1.04 0.92 0.98 0.97 1.15 1.44 0.79 0.95 0.88 0.74 0.83

126 225 238 255 291 317 447 473 471 580 612 983

2.9 1.7 1.7 2.1 1.8 1.8 1.7 2.0 2.8 2.6 2.2 1.8

Round turquoise blue beads 05 0.41 3.4 2.01

Analysis of Glass Beads and Glass Recovered from an Early 17th

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