UC Berkeley Archaeological X-ray Fluorescence Reports Title Trace Element Analysis of Obsidian Artifacts from the Andes: New Perspectives on Pre- Hispanic Economic Interaction in Peru and Bolivia Permalink https://escholarship.org/uc/item/2kr0k9c1 Authors Burger, Richard L. Asaro, Frank Publication Date 1977-06-01 eScholarship.org Powered by the California Digital Library University of California n Trace Element Analysis Of Obsidian Artifacts From The Andes: New Perspectives On Pre­ Hispanic Economic Interaction In Peru And Bolivia Richard Burger and Frank Asaro June 1977 it f Ie U. S IEnergy Research and Development Administration under Contract No. W-7405-IENG-48 he tn 'Revista del Museo Peru SIS on in LE I on 0 lysis 2 Neu Acti vat ion is 6 X-Ray Fluorescence (Rapid Scan XRF, U.C. Berkeley) 9 X-Ray Fluorescence (LBL) .. 10 Obsidian Use ..... 0' •• 13 Quispisisa Source 18 Ayacucho Type Obsidian 30 Acari e Obsidian 30 Type Obsidian. 31 as A Type i di an 32 Andahuaylas B Type Obsidian 33 CUlCO Type Obsidian 33 Titicaca Basin Type Obsidian. 37 Rare Unique Types of Obsidian 39 Models of Distribution Mechanisms 40 Discussion .... 43 .........r''''''''''' edgments. 49 50 les 0 • 54 x Bibl; i Li Fires Fi 10 i si ic in is Fi 2. c on of at the Department of Geol iversi of California, Berkel This initial study usi on Sr, Rb and was unable distinguish between of the principal types of obsidian. The graph demonstrates the way in which the Pampas Type and Andahuaylas B Type were lumped in cluster A ile the Quispisisa Source, CUICO Type, the Andahuaylas A Type, and the rare Tum.Jku were all incl in clu B. This confusion made it necessary to seek the more isticated techniques loyed at the Lawrence Ber ley Laboratory, the res ts of ich are seen in Tables 1 and 2~ and in the Append i x. L st les le tions iations neu ion at t or le it ions neu ion t Lawrence L rare Table 2. Selected trace el ition of dean obs i dian: x-ray uorescence anal is made Lawrence keley (i n p i 11 i on) . 3. i dian ana 1 x fluorescence iorL le 4. excavations ical P Table 5. i di an excavat ions at site ka i nce, Table 6. i di an ions two sis in in. v TRACE ELEMENT SIS ARTIFACTS FROM New Perspectives on spanic Economic In ion in Peru and Bolivia Ric L. Burger Frank aro INTRODUCTION This article is an introduction to the study of the distribution by trade of obsidian artifacts in ancient Peru and Bolivia. Obsidian tools were used as early as Preceramic times and continued to be popular through the Middle Horizon. The techniques of neutron activation analysis (NAA) and x-ray fluorescence (XRF) were used to identify eight main types of obsidian and to infer the locations of the natural obsidian sources. These data~ in conjunction with the findings of the archaeological research, have been used to make observations on the changing patterns of regional and pan-regional economic interaction. The data are discussed in context of the role of obsidian in ancient Andean society and the social mechanisms by which this rare material was distributed. Obsidian, a natural glass, has a hardness of 5.5 on the Moh scale (slightly harder than window glass) and is similar in chemical (but not structural) composition to granite. It is formed during volcanic activity by the cooling of viscuous lava rich in silica (over 65%) at a rate slow enough to allow volatiles to escape, but rapid enough to prevent crystallization. Because crystallization does not occur, obsidian a vitreous luster and the abili to produce conchoidal fractures struck. is fracturi characteristic is one its most i ortant qualities, p s all stone artifacts idian amen le to precision chi idian sui le on of ifac mu come ions 9 usual iary or ~ because it is e tr fies over time~ los; qualities is val ver, even some recent obsidian f 1o~"s suitable ippi ause tors s as the presence phenocrysts, spherical aggregates~ or hydration groundwater. ~ although obsidian has great potential for use in tools, it occurs rarely~ if at all, in most areas. 1 In the s, obs i dian de its exist in the highlands of Ecuador9 2 tra 1 sou Peru, 1i a. SIS re1 ive scarci obsidian suit le tools resul in obsidian over long distances. Archaeologists interested in anc i trade communication have ac ter is t 'i c s idian useful in reconstructing these movements. Obsidian from ical sites can matched th natural obsidian sources use ical fi ; nt i methods. visual qualities of obsidian are rarely of use in distin d; idian sources. Bl , gray, c ear, sidian can all occur in a single is misl arc is co ir idian collections us; sua lities. 3 on can, h and ld ; dian s at t most tive met d i in sh d 2 sources is ana el el is one 1i c t on is t idian comi one source trace e 1 ition as fingerpri le source must be 'small in ison di sources. These as ions been ri Asaro 9 and (1 9 a & b). Their i di an sources can is is case ( as n the single i dian source in lifornia)~ vari ion is extraord nari removes icul in ifi vari ion in source's el composition. itional ven i ence ana is less d of or ceramics. ies of quartzite statues n t i a 1 tional variation in a s gle qu source izer et al., contra th i dian, on al source i 1 as sources. sources. ience q s ld le measure d el tech-· niques u wi some success. are activation ana is x fluorescence ical 4 in arc ies sidian ven ience s varied consi is has imes resulted in mistaken identifications and inability to distingui between sources. The accurate measurements published thus far have been made by Perlman, Asaro, and others using NAA. Ideally, provenience studies of obsidian should begin with analysis of several samples taken from all possible sources which might have been used in iqui unate ,in the Central Andes the st little ion. sidian use was n time ish is tor' i c gives no clues for the location of idian sources. Therefore~ ne geologists nor archaeologists have a useful to location of obsidian sources. Because of is, it has been necessary work in the os i te d i rec t ion. is study, obsidian at 94 archaeol cal sites in Bolivia was analyzed to determine its trace element com- itions. These determinations were used to identi the di i dian u i di an s a di inctive geochemi intI! ich corresponds to an ivi al source raw i dian. the exact source ions are ssi in one case~ it t each i di an was thin circumscri ical a~"ea . is 1y 3 ies Old ld ans s most i ve use 4 an idian occu rs near source. di ons idian a i ic ion ion i cases is iques u in were on ana is x-ray uorescence. ion was consi an essential technique because hi ision measurement of a large el It was relied on dis tinguish between different types of obsidian found in archaeological contexts. is was done determini absolute amounts various trace elements. The results of these nations served as a guide for this st 11 ~ no t, The neutron activation ique u Lawrence is time cons 1i t s les which can be run. all, les were run is The ndings of the neutron acti i on an ali s were develop an x fluorescence techni specifical desi distinguish the different of obsidian. se whi used a more 1 ited of , were less cost An additional advantage is that it is ive. lese ini s le ible ici b e some ca are summari applied NAA to obsidian from three sites in the Departments of Cuzco Puna, Peru 1973) . XRF 32 pieces Bolivian i di an was 1i shed recent ly ila Salinas, ) . There are disturbing differences between our results and those of ila, 0.1 the samples analyzed from Tiahuanaco and Sora Sora were taken from the same obsidian fragments used in the study of Avila. " NEUTRON ACTIVATION ANALYSIS This section describes the NAA procedure used at the Lawrence Berkeley Laboratory for this study.5 To begin, the obsidian sample is cleaned of surface dirt, usually by scrubbing with water. The fragment is then pulverized by hand using a mortar and pestle of agate. One hundred milligrams of obsidian powder is measured with a Mettler balance to an accuracy of 0.1 mg. The powder is thoroughly mixed with 50. mg of cellulose binder. (Previous studies have shown that cellulose does not contain disturbing levels of impurities.) The obsidian and cellulose mixture is made into a pill (1 cm x 0.12 cm) with a hand-operated press. The .pi·lls must be standard in size in order to maintain a reproducible geometric arrangement between pill and detector during the counting of the gamma-ray radioactivity. The pills are first encapsulated ;n 0.0025 cm polyethylene foil, and then placed on edge in a radial array inside a heavy-duty polyethylene capsule. Within the capsule is an B-position jig which holds 5 unknown pills and three standards. One II standard pottery pillil ;s included in each er, placed in diametrically opposed itions.