The journal of the Center for Bead Research Volume 11, Number 1 Issue 25 1998 (10(2)
GLASS
, . , A diagram of the structure of a crystalline substance (on the left) and of glass (on the right). The·black dots are silicon, the open dots oxygen and • the shaded dots sodium (after Brill 1962:133). GLASS ANALYSIS
Fig. 2 Glass factory of the 16 century from Biringuccids Pyrotechnia (Smith. and Gnudi 1943: 133).
and t~e Al:'fALYSIS OF INDO-PACIFIC BEADS
~. The MARGARETOLOGIST is published twice a year with the most current information on bead researc~ primarily our O"TI. USA: Members: 53012 y~ats, Patrons: 580/2 years, Supporters: 520012 years, Foreign: 535. 590. $210. Upp The, last year has been exciting. It inc1uded=>;> 15-19 June: Consulting at· American e· appearances in Toronto, Denver, Chicago Museum of Natural History•.!'JYC,St. ,'and Mitineapolis,a most satisfying Bead Catherine's' GA. Expo '98 and continuing consulting with =>' 19 October,... 5 November: Bead and' Art Tour of India; stay in India formore re- the Americah Museum of Natural History, search . New York on St. Catherines, ·Georgia. I<~!{~~fg~t1~;~r,~~B~~¥~l§.!R1'1;Mlt.f was in Ghana for three months and on to Send us your email address. , the Berenike, Egypt, excavation for one. I ..J If the last digits on your mailing label got very sick the last month in Ghana and are 11:1, it's time to renew. remained so in Egypt. I have slowly recov ..J Notify us of any address changes ered since (the doctors never did figure out ..J Each classotmembership receives free what it was). Thanks to all who expressed advertising space and free Bead Identifi cation Certificates or Research Reports their concerns. I am much better now. ..J Memberships make wonderful presents A highlight of this year has been the -V Encourage your Bead Society, shop or analyses of20Indo-Pacific bead samples by institution to support us and allbeadre Ron Hancock ofthe University of Toronto, . . search groups ' . to whom I am deeply grateful. This pro © , . The Margret. Carey "Gotcha" Award has gram has answered several questions re been extended to The Bead Site. She wins garding this crucial bead industry, It is the . again. Corrections for'10(2). key finding presented in this issue: To in~ Page/Column/Paragraph/line troduce it, I enlarged on the topics of glass 211/2/4 identify to identity and glass analyses. I hope you find it 41213112 cassock to hassock stimulating. 6/112/2 bead to beads . 71113/8 em to rum The last issue (Seed Beads) has been one 91112/4 beads to bead . • of the best-received numbers to date, This 10/2/3/3 ordian:ry to ordinary is due to the tremendous interest in beading ll/1/3/6 color lined to color-lined and the desire to understand the complexi 13/11512 Libraire to Librairie. ties of the smallest beads. The success of 14/11117 Indonesia to Indonesia, Bead Expo '98 and the popularity of the Seed Bead Gallery on the thebeadsite.com are further proof ofthis, ifany is needed, Our web site, thebeadsite.com, just keeps b'ooming. Because of it, I can present all the analyses made of Indo-Pacific beads (this issue has the new ones in Table 2). To access them go to www.thebeadsite.com. F rom the home page go to Galleries, then to Color Plates for the Margaretologist, then to the version appropriate for your browser. Ifyou absolutely can '/ get ~n the;Ai1}.;: . 'Ut3:'t:eCdiri1Ortab1e}/ "";') Internet and absolutely must have copIes of ··:J~~t;ei;~;;n~};~~tifeEfeai:la;;d A# " these tables, .let m_~ ~ow"TotJr oflncfj8.CfO!$jrig.'deadll~'iih$fic1n . Happy surfing! mi·"See' ril()l'eat.~:ttle~ad~ite;com/ .' 2 The Margaretologist Vol. 11J No.1 Issue 25 1998 Glass and Glass Analysis • The world Just wouldn't be the same with- . sometimes called an "under-cooled" liq out glass .. There, would be no windows, uid. Additionally, glass does not have a bottles or porcelam bathroom fixtures, not definite meltino- point. It becomes more to mention televisions or light bulbs. And or less viscouso slowly, without a sudden where wo~ld beads be? change in phase at a precise temperature. Glass .IS so commonplace that we call The American Society for Testing and m~ny objects by that name spectacles, Materials (1979:294-5) defines glass as: mmors, laupes and tumblers. Yet the An inorganic product of fusion which has nature of glass is a matter of scientific de- cooled to arigid condition without crystallizing. bate and hardly perceived by most people. Glas~ is typically hard and brittle and has a Glass is an odd duck. It is not a strictI conchCOlda1 fracture. It may be colorless or col . y ored, and transparent to opaque. Masses or bodies ma~enal: b~t a state of matter, on par with of glass may be made colored, transparent, or solIds, lIqUIds, gasses and plasmas. It is opaque bythe presence of dissolved, amorphous or similar to solids because it is firm, but crystalline material. ' also to liquids, because it lacks a crystal"' Many solids can be made glassy if line structure (Fig. 1). melted and cooled quickly enough to pre Let's compare o-lass to more common vent recrystallization. Since the 1960s, states of matter, u~ng water as an exam- metal~ic glasses have become important pie. 'When the temperature is over 100° C matenals. Razor blades and tape recorder water is a gas called steam. The H20 heads were early uses, and other applica molecules are very excited (have high ki- tions are being developed rapidly, netic energy), move around rapidly and The precise structure of glass is under • fill any container. When the temperature de?ate. Some liken it to polymers (lo.ng drops below that point steam condenses stnngs of molecules) that charactenze into a liquid and gathers at the bottom of a plastics. Others believe it is composed of container, filling only a discrete volume. submicroscopic distorted crystals that The molecules still have considerable ki- form a random lattice. It can be thought netic energy and slip and slide around of a~ an irregular network tha~ can enclose each other. Water is not very viscous foreign atoms or molecules (FIg. 1). (heavyweight oil and molasses are more In everyday speech, and from hereon in viscous), so it flows easily. this issue, the word "glass" is not used to When the temperature drops below 0° desi~nate a ~ate of matter ?ut to refe~ to.a C. water forms ice crystals. The mole- partIcular rruxture of OXIdes. This IS. cules are bound to too-ether and no longer "commercial glass," the glass of everyday move around. 1 Ice is rigid; it is a solid. experience, Glass is firm, but highly viscous rather than strictly rigid. It has no crystalline The Glassmaking Oxides structure but a lattice or network of mole Glass is usually composed of three types cules. It is thus like a liquid, but for prac of oxides, elements combined with oxy tical purposes resembles a solid. It is gen, the most common molecules. Some are called simply iron oxide or lead oxide. Several are'named by changing the ending 1 TIleir kinetic energy now only" allows them to '" of the element to -a or -ia. Thus, the ox vibrate', as do all substances until absolute zero (ca. ide of silicon is silica, of aluminum alu '. -273° C) is reached. 3 The Margaretologist Vol. 11, No.1 Issue 25 1998 mina, of sodium soda and so on. Some Fig. 3 (adapted from Scholes ~nd Greene have special names -- potash for petas;.. 1975:38) gives an idea ofthese properties. sium oxide and lime for calcium oxide. The three major irigredients of soda-lime . Some oxides are "network fonners" that glass are drawn at 1200 to each Other. At " • create glass b:r themselves. They have the lower right, silica- gives' glass its vis atoms surrounded by four oxygen atoms cosity and vitreous character' and retards and can fonn chains and networks in ran its expansion under heat. To;·the lower" dom fashion. Of these, silicon is by far left, soda lessens viscosity, l promotes": the most important. Next to oxygen, sili thermal expansion and makes glass prone' con is the most common element in the to attack by water. At the top, lime pre Earth's crust, accounting for 27.6% of the vents solubility in water and contributes to atoms and 59% of its weight. Boron is the the tendency to crystallize, ot 'devitrify. other important network former. Other gIassmaking oxides are arranged in A second group of oxides are "network approximate relative positions:' As the modifiers." The central atoms are larger original authors noted, this 'scheme is than those of network fonners and must oversimplified since no clear-cut division be surrounded by more oxygen atoms. between the ingredients can be drawn. They do not become glassy by them Yet is it a useful schematic representation selves. but when melted with network ofthe origins of properties. formers enter the glass composition. They include such critical ingredients as soda, Devitrffication • 0",0 ("'0 MJO . potash, magnesia and lime. Densoty F'o z"o ",oJ. Durability A third group is "intermediary." Again, ~ I they do not form glass alone, but become part of the network when fused with a network former. Alumina is such an ox ~~o~\, . Fluidity ViscositY • ide, as is lead in heavy lead glass. IY~." I \ High Expansicrrf k'..o J3~)J ..s'0.z. Each glassmaking oxide plays a role in Solubility Low Expansion making glass.' Silica (usually as sand) melts at a temperature (14300 C) too high Fig. 3. See above for details. for ancient furnaces to achieve? To lower its melting· point a flux, usually an alkali Making Glass (soda and/or potash) is added, obtained There are natural glasses crea{ed by vol from alkaline deposits (Wadi Natron, the canoes (obsidian, pumice),' meteorites Dead Sea), soil efflorescence or plant (tektites), lightening (fulgurates) and in ashes. Pure silica-soda is soluble in water tense fires that can even form glass from ("water glass") and unsuitable for most the silica in plants, While ancient people applications. Lime prevents this. This used natural glasses (especially obsidian.· seems not to have been known to ancient for blades and other tools), there is no glassmakers, who added lime accidentally evidence that they employed arty as a raw as .shells or limestone impurities in the material in the manner ofgl'!-ss. i sand (Turner 1956a: 45-6T). Glassmaking is a ceramic art, ceramics Each· glassmaking oxide contributes to being the altering of earthy material by the characteristics of the finished glass, applying heat . Clay and steatite (soap stone) were the first ceramics. ., of," - That maximum \vas probably around J 100° C The~ f1:(st artificial ceramfc was faience, (Besborodov 1951: Turner 19?4a). ~ppearing .in th~ Nile Valley about 5400 '. 4 / .-' Th'e Margaretologist VoJ.11, No.1 Issue 25 1998 years ago. Faience has a core of (usually) of heat. Small ones ("seed") rise slower, quartz particles melted only enough to and those of 0.01 mm take as long as a adhere where they touch' (sintered) and an year and a half to rise as little as a meter. • exterior glaze, a true glass. As an inde Added in the trivalent (As203) form, ar pendent synthetic material, glass was a senic converts to the pentavalent state technological advance made in Mesopo (~OlO) as the batch is heated, absorbing tamia (modem Iraq) some 4500 years ago. oxygen. At maximum temperature, it Glassmaking . requires several steps. slowly reverts to ~03, releasing oxygen. Sand (including the lime) and alkalies are Since the freed gas cannot easily form crushed as finely as possible. Today the . new bubbles, it joins small bubbles in the alkalies are washed, but the phosphorus in batch, enlarging them and causing them to most ancient glasses indicates that this rise and escape. As the glass cools, some was not often done. These are put into a AS203 converts to As4010, absorbing more furnace (sometimes with colorants) and of the remaining oxygen (Scholes and heated to about 7500 C for several hours Greene 1975:21 or days while being stirred (Fig. 4). The ingredients sinter and the resulting opaque, unpromising material is called "frit." Frit was sometimes repeatedly quenched in water to skim off impurities. It is then powdered and mixed with glass called ','cullet" and perhaps colorants The 0 whole is heated agai~ to 10500 or 11 00 C, until it melts into molten glass (Fig. 5). • Other Glass Ingredients Molten silicate glass is a universal solvent of oxides. It will dissolve water and gas ses, though their volatility at high. tem peratures means that only small amounts Glass is normally transparent or transl~ are included in most glass. Glass will cent. Masses of bubbles or other impuri leach out alumina, iron oxide and other ties opacify glass, as do incomplete vitri- ' oxides from the clay of the crucibles and fication or devirification due to the pres furnace: A complete list of all glass con ence of crystalline structures.. Antimony stituents, especially in older glasses made was used as an opacifier all but exclu 3 with impure components, can be nearly as sively until about the first century AD , long as the periodic table itself after which tin dominated. Phosphates .Other ingredients in glass are purposely . (often as bone ash) came into use in the added. These include those used for fin late· 17th century, arsenic in the 18th cen ing, op'acifying and coloring the glass. tu~ and the now common fluorides in the Fining agents remove bubbles. For 19 century (Turner and Rooksby 1959; s'oda-lime glass, arsenic and antimony are Henderson 1985:285-6). used. Both work similarly; arsenic is the The colors imparted to glass are a com . example used ·here. Large bubbles, 1.0 . plex study. 11.any ingredients color glass, .• mm or so ~n diameter, rise'quickly .in glas's .: and can be driven off by a couple of nours 3 Red glass was rendered opaque by the suspended copper particles that imparted the color. 5 .' The Margaretologist Vol. 11 , No.1 Issue 25 1998 " and most colors can be made more than glass. Large amounts of iron are also used '. one way. The nature of the furnace, to rnake "black" (actually deepigreen). o whether. open, oxygenated or muffled Modem chemistry has identified the (oxygen-:starved) alters the final color. So elements that make up the unjverse. As does the fuel used, other oxides present, each rnetal was identified, it -was tried in _," the amount of oxide used and the state glass, at least experirnentally .. Sorne ele (valence) of the oxide. Colorants may be rnents unknown to the ancients have be added as unrefined ores, metals, flit or come important glass colorants. These glass (cullet). The best work on colorants include uranium (giving greens,. yellows -~ W 195 and orange), selenium (pinks, reds and the < most common rnodern "glassmakers' soap") and cadmium (as cadrnium sul fide), yielding a bright yellow. Glass Analysis Given that glass has so rnany constituents and a wide choice arnong possible ingre dients, knowing the cornponents of glass can tell us something about its .origin, background, date or other useful informa- , tion. At least that is the hope. In practice, glass analysis is an. expensive proposition, either or both in time .and rnoney. Know ing the makeup of a piece of glass is only When glass is made, it is usually green, . part of the story; it is also ess~ntial to in o called "bottle-green," as it is the color of terpret the inforrnation correctly. cheap bottles .. It is due to the universal The pioneer glass analysis was. by the impurity of iron, but even that is not sirn~ German chemist Martin Heinrich Kla pIe. Ferrous iron (FeO) produces a yellow proth, the discoverer of uraniurn, titaniurn color, while ferric (Fe 03) makes blue. 2 and zirconium. He was interested in the Cornbined, they form green shades (Biek colorants of sorne' Rornan rnosaics' frorn and Bayley 1979: 14-5). It is extremely Capri and devised a way to analyze the difficult to remove. Look edge-on at a sarnples, which he, published in 1798. modern "clear" pane of glass and note the Sorne of· his methods and intt?rpretations color that is still present. were ahead of his tirne (he re~soned that The proper applications of two anciently different states of an elernent. can make known metals, iron and copper, produce a different colors), while others seern oddly wide range of colors. Two others were lacking. He did not' test for alkalies, but long used' to color glass. Cobalt is a this . was before· sodium and· potassiurn strong colorant that imparts a rich blue in were identified as separate elernents. srnall quantities. Manganese in srnall The chemical rnet~'od (or "wet analysis") amounts yields pink. When suitably con h~ used became the basis for ;rnost glass trolled it cancels out bottle-green, forming' analyses until recently. It is a technique clear glass, ,giving it the nickname requiring rnany steps: powdering the sam "glassmaker) soap." In higher concen pLe and washing, heating and treating the trations, it rnakes a violet color and in still decreasing residue ~with cherni~als known . larger amounts a very dark or "black" o 6 The Margaretofogist Vol. 11, No.1 Issue 25 1998 to react in certain ways with various eJe 100%. Different results may corne from ments. A detailed description of his work different. or even the same laboratory be is in Caley (1962:13-15). It was not for cause of calibration errors or because • half a century that glass analyses of higher glass is not homogeneous. Sometimes quality were performed. closely allied groups (iron and aluminum, When vaporized and illuminated, ele soda and potash) are not separated. There ments will emit characteristic colors. is no general agreement on which oxides Most· high school chemistry students re of a given metal are present, for example member putting a powder onto the tip of a MnO or Mn20 3 (Weyl 1959: 121). platinum wire and placing it into a flame Despite these obstacles, glass analyses, to observe the color. Early in this century, especially those done with the newer arc spectrographs using an electric arc that methods, hold out great promise as tools simultaneously volatized and illuminated for understanding the history and signifi the substanCes tested were in use. Dif cance of glass and glass beads. However, fraction gratings separate the .colors emit the proper interpretation of the results is ted. However, only relative amounts of crucial in reaching sensible conclusions. elements could be determined at first, though this has· been improved. The The Wby and How of Glass Analyses method is as destructive as wet analysis. Analyses of glass and glass beads have The introductions of more sophisticated been done for different motives. Many techniques have proven valuable. X-ray seem to be done simply out of curiosity, fluorescence needs either large or pow perhaps looking for a key ingredient (usu dered samples and examines only the sur ally colorants, alkalies or lead) or just to face of an object, a problem if there is any see what is in the glass. In these cases, corrosion. A refinement of this method, interpretations are usually weak. (Some • the electron microprobe, analyzes only times it was not even recognized that clay very tiny areas, and thus records varia or shell beads were included with the tions in glass, which is not homogeneous. analyses of glass beads.) (For these older methods see Smith 1963.) There is nothing wrong in such analyses. Still newer methods have been devel In time, someone comes along and col oped. Neutron activation bombards the lects them, interprets them and draws con sample, making the elements radioactive. clusions. This has not yet been done for They can be determined as they decay beads, but has been done for glass. The (many elements have very short half most valuable such summary is by Turner 4 lives). The PlasmaQuad removes a tiny (especially 1956a, b, c ), unfortunately sample with a laser and determines its never published in book form. Caley makeup via mass spectrometry. (1962) is less informative, but still useful. Yet with all this technical wizardry Another approach is . to formulate a problems persist. Results are given in problem that can be answered by analyses, percentage of weights and differ if ele including previously published ones .. This ments or oxides are reported. Not all ele holds out more promise than the publish ments are always reported because they ing of only a few analyses at a time, and were not all looked for. Errors mean that has been used successfully in several the totals rarely add up to 100%. ·If they do, silica.was likely determined by adding 4 : These are three of six papers published in this up the other oxides and subtraGting !rom journal from 1'954 to 1959. Not all are cited'here, •• but all are listed. in the reference section. 7 , ! The Margareto[ogist. . Vol. 11~ No.1 .lssue2S· 1998. cases. Some of those with the broadest two ,scholars chose different ; groups 'of'" implications are considered here. trace elements, their work canrlot even, be The earliest was done for Chinese compared to each other. Davison's ,con glasses, including many beads (Ritchie clusions were ambiguous. I believe that 5 • 1937, 'Seligman and Beck 1938). It con Saitowitz's has many problems. ,'., firmed the heavy lead content of early To summarize, a program of glass (bead) Chinese glass and revealed a surprising analysis is optimally based on a carefully barium constituent. It was done by arc planned agenda to answer. spepific prob~ spectrometry, so that precise percentages lems. Apples and oranges should not be were not available, and had few post-Han compared. Specimens shpuldtbe, cqosen examples to consider. carefully as to origins and assoCiations .. , .' The cooperation of Edward Sayre as the Henderson. ( 1995 :67) outlined the types " chemist and Ray Smith as the collector is of questions that glass analysis can poten the widest such study (Smith 1963, 1969, tially answer. They include jdentifying Sayre and Smith 1967). It has' revealed the raw materials and colorants, used jn patterns in glass composition over 3000 glass and finding, links between glass years in Europe, Africa and western Asia. composition and bead types, dates, manu- , In the Indian context, papers presented at facturing sites and" other glass products; . the Archaeometry of Glass session of the With this information, much can oe , XIV ,International Congress On Glass learned about glass beads, their ongm, (Bhardwaj 1987) contain many analyses . trade and cultural affiliations .. ~: and some interpretations of the results. While useful and often citing beads (vir tually the only glass product in india for a long time), they lacked a rigorous agenda for interpreting the results. No attempts • were made to pinpoint glass beadmaking , sources and to compare glass from them. India was treated as though all glass from the vast region should be the same. As for trade beads in the Americas, an excellent beginning was made by the ar chaeo'Iogist Ian Kenyon and RG.V. Han cock and his students as the investigating scientists (Hancock, Chafe and Kenyon 1994, Kenyon, Hancock and Aufreiter 1995). Unfortunately, Kenyon's death has put this program on hold. Two programs have been developed for 5 A perceived "cerium depletion" led Saitowitz to conclude that the A.f:tican beads came from Egypt • glass beads in Africa (Davison 1972; rather then India or Indo-Pacific beadmakers. Saitowitz, Reid and van der Meer 1996). However, there is considerable overlap among the These are not as useful as they might have, be,ads. the Egyptian beads werenoti all ce~y been., Both chose to investigate trace made in Egypt, the Indian examples were from elements found in tiny amounts that were Arikamedu.. while Mantai or Srivijaya were more likely sour~es, her assumption about alkali sources not been purposely aqded. There are no is !11isleading; there are alternate explanations fq~ parallel analyses for these and since the. cerium depletion and the beads. were' not· carefully sel~cted; they even include aVenetian green heart. '. 8 / The Margaretologist Vol. 11, No.1 Issue 25 1998 • Analyses of Indo-Pacific ·Beads Thailand. These were apparently the east Background ern and western ports of Funan (or close Indo-Pacific beads are small monochrome to the ports), and facilitated commerce drawn glass beads, the first seed beads. between India and China. They were the dominant beads in much of In the 7tlt century, Funan was overrun by the Old World for 2000 years. They were the Khmers of Cambodia and lost its role the most important trade beads, perhaps In commerce. This was assumed by t • . i WEST l!;LI8/.. • MPLA Y~rA Se.lnsinlJ "'- ~ ~SINGAJ'ORE ,. \ t ~ Vljayll ~~.::: AI • the most important trade item, in history. Srivijaya, based in Sumatra, with its Readers of the Margaretologist· and capital at modern Palembang (anciently some of my other works know that I have probably called Vijaya). Srivijaya con been researching these beads for twenty trolled much ofJava and the Malay Penin: years. As this work drew to its conclusion sula, thus the waterway (the lVIalacca with the Arikamedu final report and. a Strait) and the overland routes that con book on beads in the. Asian maritime nected India and China. trade, questions about them persisted. Four sites in Srivijaya made Indo-Pacific As far as can be determined, these beads beads: Vijaya, Kuala Selinsing and Sungai were first made at Arikamedu, on the Mas, Malaysia and Takua Pa, Thailand. Southeast coast of India. A few miles Kuala Selin sing may never have been a . south·ofArikamedu the port of Karaikadu port, shipping its products out from Sun was occupied in the early centuries AD. It gai lVIas. In the 10tlt century, Sungai lVIas also made them, probably in conjunction succeeded Kuala Selinsing as beadmaker. with Arikamedu. Takua Pa was occupied only in the 9th Around the first century, AD, some century, perhaps an attempt by Srivijaya Indo-Pacific bead makers migrated from to control the overland routes. Arikainedu to three other locations. One Mantai, Sri Lanka, was abandoned in the was lVIantai, in northern Sri Lanka, then l.Oth century. Srivijaya lost power in the m al1i~d with South· India. The other two 12 centurv .. All this time, Arikamedu were in Funan, the first state in Southeast .continued t~.·make beads, and' became the • Asia: Oc-eo, Vietnam'and Khlong Thorn, . only bead maker again around the 12m 9 , ' The Margaretologist Vol. 11, No.1 Issue 25 1998 l century. By the 17th century it, too, was in northern India or locally with ingredi abandoned and the beadmakers moved ents from Firozabad.6 north to the village they currently occupy, This was seven sites and fourteen beads, o Papanaidupet, Andhra Pradesh. leaving six slots. Because we have dated ' This is a remarkable story of beadmak wasters from Arikamedu, I took four sam ing in at least ten sites in si~ modern ples from there and added an orange bead countries for more than 2000 years. It has from Kuala Selinsing. and th~: distinctive been pieced together by identifying the green-blue glass from·Vijaya.: Finally, I unique glass wasters produced by the chose two beads from Gilimanuk, Bali: a I beadII1~ng method, particularly the tube first/second century importing site to see. ' drawing technique. ifwe could source its' beads. ' I sent these samples. to Ron Hancock, Problems and a Program who analyzed them at the SLQWPOKE-2 I had the outlines of the Indo-Pacific bead Reactor Facility. He placed each into a story, but was missing many ofthe details. small plastic vial and sent it into the heart In particular, I wanted to know the source of the reactor where it was bombarded by ofthe glass. ',Some'scholars had suggested radioactivity for about a minute. The vial that it came from the West as scrap glass, was then retrieved' and put into a gamma but the published analyses of beads in this ray detector. Each element emits a char region indiCated this was not so (Francis acteristic peak along, the gamma ray spec-. 1988/9:4-9). Was it made at one or two trum. The height and strength of the peak Indo-Pacific centers and shipped to the indicate the amount of the element present others, to work or did each center make its and a computer program interprets these own? In particular, what was the nature as percentages (or part's per minion). of the glass at Arikamedu, the subject of The brief bombardment affected. ele o my most intensive study? ments with short half-lives. "Within a few Over the years, I collected Indo-Pacific weeks, the samples were radioactively bead samples from importing and bead cool enough to be returned.' Had he bom making sites in South and Southeast Asia barded the samples longer they would· from the excavators (surface finds for have detected elements with longer half-. . Karaikadu) in hopes of having them ana lives, but would have remained radioac-, lyzed. My chance came when Ron fIan tive for a long period and could not be cock of the University of Toronto offered . returned. This meant we could not detect to analyze 20 samples by neutron activa- ' certain elements, notably silica and iron. J tion with the SLOWPOKE-2 Reactor. did not think the amount of silica was cru-' The first decision was choosing samples cial to the investigation. The lack of iron ,,' to analyze. I concentrated on beadmaking In our analyses was the only drawback. sites. I chose the dominant colors of There are also other analyses: from some opaque red and dark translucent blue. I ' of these sites previously published. In had no samples from Oc-eo. The Mantai cluding our analyses, 'there are now nine:.., samples. were being analyzed elsewhere teen available for Arikamedu, fourteen for and not ayailable. I eliminated Papa Kuala Selinsing, eleven for Oc-eo and naidupet, as its glass is made at Firozabad 'seven for Takua Pa. Those from Karai 6 Firozabad bas long been fue';:gfuss capital" of . O' India. but is unrelated to the Indo-Pacific industry. 10 /1 i The Margaretologist Vol. 11, No.1 Issue 25 1998 kadu, Khlong Thorn, Sungai Mas and Vi are so different from Western glasses that iay3 have only been done in this ",retram. they cannot be related. Tables showing all the' analyses of Indo- ' • Pacific beads are posted 00 , One or Many Glassmaking Centers? www.thebeadsite.com. From the, home Not only is the glass from the Indo-Pacific page click on Galleries, then Color Plates bead making sites different from Western for the MargaretologisJ then to Netscape or glass, but it differs among the sites' as IExplorer Versions (depending upon your welL The red glasses are similar,but the browser) for issue 11(1)~ other colors have distinct signatures. Some earlier analyses have drawbacks. The Arikarnedu non-:red glass stands , For Oc-eo, soda and potash were reported apart as it has potash as its major alkali. as soda. only. In some or all but one of the The glass of Kuala Selin sing has very ,early analyses for Kuala Selinsing and high alumina and very low manganese, Takua Pa only silica" alumina, lime and separating it from all the others. Oc-eo ,copper were analyzed 'chemically and the and to some extent Takua Pa share the rest by arc spectrometry. high alumina content, but only Vijaya .' , shares the low manganese concentration . The Results Only Vijaya made translucent green-blue Glassfrom the West? , glass, which also sets it apart (Mantai The question of whether the raw glass for made a unique opaque blue-green glass). Indo-Pacific beads carne from the West There are some similarities. The glass of and was merdy worked in Asia was dis Karaikadu and Arikamedu are virtually cussed a deca.de ago (Francis 1988/9:4-9), identical, not surprising given their . reasoning that it was not. The new analy-. proximity. The glass was either made s¢s strengthen that con'clusion ' with the same recipe or at the same place. • For opaque red (and orange) beads, the The major difference between the glass. Indo-Pacific group differs significantly of Oc-eo and Khlong Thorn is that the from glass of this color in the West be.:. o KhlonI;;;l Thorn blue is colored. in the same cause it lacks .lead. Lead aids the dis way as the Arikamedu blue (see below). solving of the copper to make this color, These two places were politically con and virtually all red glass in the West has nected and might have had one glass heavy amounts of lead. There are a cou making center. We need more analyses pie of exceptions, but they are very rare. from both places. We have only our two, On the other hand , no Indo-Pacific red. 'from Khlong Thorn and the published Oc glass has any signifioant lead content. eo analyses need to be supplemented. At Arikamedu, the blue, black and violet .' The other possible glass group is from glasses have potash as' their major alkali, Srivijayan sites: Vijaya, Takua Pa and. while this was not the case for Western ' Sungai Mas (but not Kuala Selin sing, glass in the first millennium. The alumina, which may be earlier). There may have in glass from Oc-eo, Takua 'Pa and espe been a single origin for their glass, but we cially Ku~la $elinsing is very high com need more analyses to be sure of that. pared to glasses in the West. Moreover, the m.agnesium content at Vijaya and Glassmaking at Arikamedu Kuala Selinsing is extremely low com A major surprise to me was what we o pared to any Western gl~sses. In sum,. the learned about .glassmaking at Arikamedu. red. glass from'all these sites and the The different alkalies for different c010rs glasses of other colors from most of them 11 '},- '", '.: \ , ., The Margaretologist Vol. 11J No.1 Issue 25 1998 ' • f (soda for red, potash for the others) were were most likely responsible for bringing already known. diamonds (for drilling)" agate, carnelian The colorants are also interesting. Cop and almadine garnet from this area, as 't • • i - . ; per was used for opaque green and red. well as wad, and. free copper: for the • 1 • Iron was used for translucent green (never glassmakers of Arikamedu. I made into Indo-Pacific beads), some of Not all wad has'cobalt, and·the deposits· the "black" and presumably opaque .yel without cobalt .would have made violet low. Manganese was used for the violet and black glass. No d~ubt it was quiCkly and the rest ofthe "black." learned which deposits would produce But what about the second (to the red) blue glass and which violetJblack. most popular color, the dark blue? It is a The manganese.:.potash-cobalt combina rich shade, often purplish 8 blue. It looks tion for dark blue glass' is also evident like a deep cobalt blue, but no cobalt had elsewhere. This includes Giliinanuk,' the been detected. The first analysis of Ari importing site in Bali, which evidently g~t kamedu beads by Subramanian (1950) its beads from Arikamedu (there were was of this color. He found a high man collar beads there too, also froin Arika ganese concentration and rightly noted medu). A dark blue bead from Takua Pa that the violet of manganese is shifted to and one from Kuala Selinsing also had ward the blue end of the spectrum in a manganese-cobalt, but not potash' ,.sug,:" . potash environment. gesting that wad might have been im: However, the SLOWPOKE analyses ported from India bythese·glassmakers. shows that there is cobalt in small but sig The judicious choice of only 20 samples nificant amounts in the blue beads. Being has been revealing. . The new analyses \ a strong colorant this can accdunt for the confirm Indo-Pacific glass as Asian anp. bLue,' especially with the manga 8 the independence of the beadmaking sites, nese/potash combination. Yet, the cobalt most even making their oWn glass, The • is in such small amounts it cannot have revelations about the Arikamedu dark blue' been purposely added. Had it been there glass and the' early import of Arikamedu would also have been a corresponding ar beads to Bali are also important. senic content, since cobalt ores are arsen ious. And even if it were, why would the References and Further Reading manganese have been added? American Society for Testing an~Materia1i1 The answer must lie in the raw material ·1979 Compilation ofASTM Standard Definitions ASTM Committee on Technology, Philadelphia used, and that has to have been the impure (4 th ed,) , manganese ore with the unlikely name of Besborodov, .M...A. 1951' A Chemic31 and Tech wad (also called "bog manganese"). Wad nological Study of Ancient RuSsian Glasses and often contains a small amounf of cobalt. Refractories Journal of the Society of Glass It is available in India, and its source was Technology 41: 168-84T. Bttardwaj, ac. , ed.· 1987 Archaeometry of accessible to Arikamedu. It is found in Glass, Proceedings ofthe Archaeonu:!try Ses~ion southern India' in the region between the of the ...YIV International Congress On Glass Krishna and Godavari Rivers. 1986 New Delhi Indian Ceramic Society, Cal Not only is this region close to Arika cutta' . medu, but it is also the area that I have Biek, Leo and Justine Bayley 1979 Glass and other vitreous materials World Archaeology previOUSly identified [1993 6(2):4] as the 11(1): 1-24. " " source tor most of the semi precious stones Brill, Robert H. 1,962: A Note on the Scientist's cut there. The young Pandukal horse'men Def)nitiC!n of Glass Journal of Glass Studies 4:127-38. .' 12 The Margaretologist Vol. 11, No. 1 Issue 25 1998 r">. CaJey, Earle R 1962Analyses of Ancient Glasses Smith, Cyril S. and Martha T. Gnudi 1943 The 1790-1957 Coming Museum, Coming. Pirotechnia of Vannoccio Biringuccio MIT Davison, Claire C. 1972 Glass Beads in African Press, Cambridge. Archaeology Ph.D. thesis, University of Califor- Smith, Ray W. 1963 The Analytical Study of nia, Berkeley. Glass in Archaeology, pp. 519-28 in Don Broth- Francis, Peter Jr. 1988/9 Glass Beads in Asia. well and Eric Higgs, eds. Science in Archaeology Part 1. Introduction Asian Perspectives 28(1):1- Basic Books, New York. 21. - 1969 History Revealed in Ancient Glass Na- Gillispie, Charles C. 1959 Diderot Pictorial En- tional Geographic 126(3):346-69. cyclopedia of Trades and Industry Dover, New Subramanian, R 1950 Analysis of Ancient Glass York. Beads Current Science 19:19-20. Hancock, RG.V., A. Chafe and L Kenyon 1994 Turner, W.E.S. 1954a Studies of Ancient Glasses Neutron Activation Analysis of Sixteenth- And and Glass-Making Processes. Part 1. Crucibles Seventeenth-Century European Blue Glass Trade and Melting Temperatures Employed in Ancient Beads from the Eastern Great Lakes Area of Egypt at about 1370 B.C. Journal of the Society North America Archaeometry 36(2):253-66. of Glass Technology 38:436-43T. Henderson, Julian 1985 The Raw Materials of - 1954b Studies of Ancient Glasses and Glass- Early Glass Production Oxford Journal of Ar- Making Processes. Part II. The Composition, chaeology 4(3):267-91 Weathering Characteristics and Historical Sig- - 1995 The Scientific Analysis of Glass Beads, nificance of Some Assyrian Glasses of the pp. 67-73 in M. Ramussen, U. L. Hansen and U. Eighth to Sixth Centuries B.C. from Nimrod Nasman, eds. Glass Beads, Studies in Technol- JSGT 38:445-56T. ogy and Culture vol. 2, Historical- - 1956a Studies in Ancient Glasses and Glass- Archaeological Experimental Centre, Lejre. making Processes. Part Ill. The Chronology of Kenyon, L, RG.V. Hancock and S. Aufreiter the Glassmaking Constituents JSGT 40:39-52T. 1995 Neutron Activation Analysis of AD 1660- - 1956b Studies in Ancient Glasses and Glass- 1930 European Copper-Coloured Blue Glass making Processes. Part IV. The Chemical Com- Trade Beads from Ontario, Canada Archaeome- position of Ancient Glasses JSGT 40:162-86T. try 37(2):323-3.7. - 1956c Studies in Ancient Glasses and Glass- Morey George W. The Composition of Glass Sci- making Processes. Part V. Raw Materials and entific Monthly 42:541-54. (also Supplemental Melting Processes JSGT 40:277-300T. Publication 23, Camegie Institution of Wash- - 1959 Studies in ancient glasses and glassmaking ington). processes. Part VI. The composition and physical - 1954 The Properties of Glass Reinhold, New characteristics of the glasses of the Portland Vase York (2nd ed.). JSGT 43:262-84T. Ritchie, Pat rick D. 1937 Spectrographic Studies Turner, W.E.S. and H.P. Rooksby 1959 A Study on Ancient Glass Chinese Glass, from Pre-Han of the Opalising Agents in Ancient Opal Glasses to Tang Times Technical Studies in the Field of throughout Three Thousand Four Hundred Years Fine Arts 5(4):209-20. Glastechnische Berichte 8:17-29 Saitowitz, Sharma J., David L Reid and N.J. WeyJ, Woldemar A. 1959 Coloured Glasses van der Meer 1996 Glass bead trade from Is- Dawson's, London (reprint). lamic Egypt-to South Africa c. AD 900-1250 South African Journal of Science 92:101-3. Table 1 Some elements found in l!lass. Sayre. Edward V. and Ray W. Smith 1967 AI = aluminum Mo = manganese Some Materials of Glass Manufacturing in An- As = arsenic Na = sodium tiquity, pp. 279-311 in Martin Levey, ed. Ar- B = boroo P = potassium chaeological Chemistry University of Pennsyl- Ba = barium Pb = lead vania Press, Philadelphia. Ca = calcium S = sulfur Scholes, Samuel R and Charles H. Greene 1973 Cl = chlorine Sb = antimony Modern Glass Practice Central Book Co., Co = cobalt Si = silicon Taipei. Cu = copper So = tin SeJigman C.G. and H.C. Beck 1938 Far Eastern Fe = iron Ti = titanium Glass: Some Western Origins Bulletin of the Mu- Li = lithium V = vanadium r: seum of Far Eastern Antiquities 10:1-64. Me = maznesium Zo = zinc 13 '. f ,~ TABLE TWO SLOWPOKE-TORONTO ANALYSES OF INDO-PACIFIC BI;:ADS AND GLASS (tn percentage of element) -f :::r _,Cll CI Co Cu~~~__ Mn -Nl~§_l1__ Ti V A!j. K Sh CD ~_~_+__?:SG__(_).7~ :::;a;oq3. -.!~.~ __~().5±-~~~5 8.72 «l.()9 <0.01. 0.008 :::;0.007 4.2L .. 50.00R I s: 02 kH7 (tn :So dOl :::;O.O]-l!· 2.69 L,45 009 20() l ~! ~~ .-). 't. ''''''i ~ .\ 'r • "~ ~;? .. ! ' . ,~" 'I"' "t f ·1· '1 ) 1 '\ .'" .. J ,. ' ~' ,. ~ ~. (. ~. . 1 . , .; •\ .: - \~t,5\:~