Instrumental Neutron Activation Analyses of Metal Residues

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Analyses of Metal Residues Excavated at Tel Dan, Israel M i r e l a C . Manea-Krichten1, Nancy Heidebrecht2, and George E . M i l l e r 1 2

1

Department of Chemistry, University of California, Irvine, C A 92717 Department of Ancient Near Eastern Languages and Cultures, University of California, Los Angeles, CA 90024

Instrumental neutron activation analysis was used to determine con centrations of several major and trace elements in samples of heavily corroded residues found in crucible fragments excavated at Tel Dan, Israel. The residues were mostly hard, metallic phases admixed with nonmetallic inclusions that appeared to be ceramic material from the loose porous interior of the crucible itself. The objective was to iden tify the metals that had been melted in these crucibles. A method is described that attempts to separate nonmetallic and metallic phase data. In comparison to previous reports on analyses of source ma terials thought to have been used at Dan in this period (Late Bronze II Age-Early Iron I Age: 1400-1000 B.C.), high gold concentrations were found. These appear to be correlated to arsenic and antimony concentrations. This finding is discussed in relation to possible changes in the source of tin at this period.

^NEUTRON ACTIVATION ANALYSIS IS A VERY SENSITIVE TECHNIQUE for trace e l e m e n t d e t e r m i n a t i o n s i n various samples. If there are no elements that m u t u a l l y interfere, the p u r e l y i n s t r u m e n t a l v e r s i o n of this m e t h o d is often chosen for its established advantages such as accuracy, speed, sensitivity, simultaneous m u l t i e l e m e n t d e t e r m i n a t i o n , a n d sample p r e s e r v a t i o n (J). F o r these reasons, i n s t r u m e n t a l n e u t r o n activation analysis (ΙΝΑΑ) was a p p l i e d to samples taken from a series of m e t a l - w o r k i n g residues excavated at T e l D a n , Israel, from 1985 to 1986. 0065-2393/89/0220-0199$06.00/0 © 1989 A m e r i c a n C h e m i c a l S o c i e t y

Allen; Archaeological Chemistry IV Advances in Chemistry; American Chemical Society: Washington, DC, 1989.

200

ARCHAEOLOGICAL CHEMISTRY

T h e city of T e l D a n , located at the b o r d e r of what are n o w Israel a n d L e b a n o n , has b e e n the center of m u c h archaeological interest. It is located o n an established N e a r E a s t e r n t i n trade route that o r i g i n a t e d s o m e w h e r e near Susa d u r i n g the M i d d l e B r o n z e A g e (2). T h e same trade route s u p p l i e d t i n for C r e t e . T h e source of c o p p e r throughout this t i m e was postulated to be C y p r u s . T e l D a n ' s i n c l u s i o n i n the M a r i texts attests to the significance of m e t a l w o r k i n g at D a n (or L a v i s h as it was t h e n known) (3-5). F u l l details of the archeological finds a n d context are r e p o r t e d elsewhere (6). A t T e l D a n , two m e t a l - w o r k i n g areas have b e e n located just i n s i d e the u p p e r city gate system o n the southern p e r i m e t e r of the m o u n d . A v e r y large w o r k s h o p ( A r e a A - B ) has b e e n dated to 1100-1000 B . C . S m a l l e r s u b sidiary w o r k i n g areas f o u n d slightly to the n o r t h (Area B - l ) indicate c o n s i d erable c o n t i n u i t y i n w o r k i n g m e t a l at this site from E a r l y I r o n I A g e (ca. 1100 B . C . ) back to the L a t e B r o n z e H a A g e (ca. 1400 B . C . ) . T h e w o r k s h o p contents d i s c o v e r e d i n A r e a s B - l a n d A - B d u r i n g 1984 a n d 1985 i n c l u d e steep-sided t h i m b l e - s h a p e d crucibles w i t h residues; c e r a m i c tuyeres; a n d stone, b o n e , a n d h o r n tools. I n A r e a B - l , the c r u c i b l e w o r k i n g area was scattered o n t a m p e d earth surfaces. I n A r e a A - B there was an extensive c o b b l e d area w i t h c r u c i b l e fragments i n situ a m o n g the cobbles (7). M o s t of the samples w e r e taken from c o r r o d e d , dense m e t a l l i c residues f o u n d i n fragments of thick, flat-base porous ceramic c r u c i b l e s , v e r y s i m i l a r to those d e s c r i b e d b y Tylecote (see ref. 8, p. 20) as type B 4 excavated at sites near T i m n a a n d T e l Qasile (9, 10). T h e residues m a y b e what Tylecote c a l l e d " i n t e r n a l s l a g " (8, I J , 12). A s no e v i d e n c e of s m e l t i n g activity was n o t e d , these residues w e r e p r e s u m e d to b e from b r o n z e a l l o y i n g a n d p u rification activities for artifact p r o d u c t i o n at D a n , e v e n t h o u g h no artifacts w e r e located i n the v i c i n i t y . E x t e n s i v e a l l o y i n g was n e e d e d before fashioning artifacts, as there was purification (13). T h e established. T h e f o r m of m e t a l w i t h c e r a m i c challenges.

little benefit to the smelter i n c a r r y i n g out extensive ore s m e l t i n g site, be i t at D a n or elsewhere, is not of the samples, best d e s c r i b e d as a h a r d e n e d " f r o t h " inclusions, was somewhat u n u s u a l a n d posed several

Sample Identification • Samples 806, 807, 808, 809, 1006, 1008, 1009, 1010, 1011, a n d 1014 are from w o r k s h o p area A - B that was excavated i n the 1985 season. • Samples 801, 802, 803, 804, 805, a n d 1015 are from area B - l (dated to L a t e B r o n z e A g e I / L a t e B r o n z e H a A g e transition period) that was excavated i n the 1985 season. • S a m p l e 1012 is from a s m a l l p i n - s h a p e d m e t a l fragment that was f o u n d i n connection w i t h the L a t e B r o n z e A g e crucibles i n area B - l .


10.

MANEA-KRICHTEN ET AL.

Metal Residues:

INAA

201

• S a m p l e 1013 is similar to sample 1012 a n d was also f o u n d i n B - l , b u t i n an earlier M i d d l e B r o n z e I I A g e / L a t e B r o n z e I A g e destruction l a y e r F o r c o m p a r i s o n , similar types of materials f r o m another site w e r e s a m p l e d . Samples 1003 a n d 1004 are from T e l A k k o o n the M e d i t e r r a n e a n coast a n d are a t t r i b u t e d b y the excavator to the S h e r d e n , a group of c o a s t - d w e l l i n g peoples (1400-1200 B . C . ) . S a m p l e 1003 is f r o m A k k o V I , a n d 1004 is from Akko VII.

Background T h e o r i g i n a l interest i n these excavated samples s t e m m e d from the i m p o r t a n t role of b r o n z e a n d the historical i m p l i c a t i o n s of the extensive t i n trade routes i n the M i d d l e B r o n z e A g e (2200-1600 B . C . ) . A s b r o n z e m e t a l l u r g y d e v e l o p e d from the e a r l i e r use of c o p p e r a n d arsenical copper, t i n sources b e c a m e v i t a l (14). B y the M i d d l e B r o n z e A g e , the l i m i t e d d i s t r i b u t i o n of t i n deposits t h r o u g h o u t the w o r l d a n d the a m p l e s u p p l y o f c o p p e r w e r e w e l l - k n o w n , a n d extensive t i n trade routes h a d b e e n established to s u p p l y the m e t a l l u r g i c a l centers of the w o r l d w i t h this t h e n - c o n s i d e r e d " p r e c i o u s " m e t a l (15-16). T h e U g a r i t i c tablets from Ras S h a m r a , h o w e v e r , indicate a severe d r o p i n the value of t i n a r o u n d the L a t e B r o n z e A g e (1400-1200 B . C . ) . It has b e e n postulated (17) that this d r o p was r e l a t e d to the discovery o f m o r e accessible sources of t i n .

General Considerations T h e p r i m a r y objective of o u r research was the analysis of the mixtures o f pottery (crucible wall) a n d c o r r o d e d m e t a l residue (slags) b y I N A A i n an attempt to p r o v i d e information o n the metals u s e d at D a n . I n a d d i t i o n , two small m e t a l fragments, w i t h little or no c e r a m i c adhesion w e r e s a m p l e d . A l l materials w e r e h i g h l y c o r r o d e d a n d s h o w e d various green, grey, a n d b r o w n encrustations, a n d a c o m p l e t e absence of obvious m e t a l l i c surface. A s m e n t i o n e d earlier, the samples w e r e v e r y heterogeneous. E i t h e r the m e l t i n g process was i n c o m p l e t e a n d the h i g h e r m e l t i n g solids that r e m a i n e d closest to the c r u c i b l e walls w e r e u n e v e n l y m i x e d a n d not r e p r e sentative of the c o m p l e t e l y m e l t e d p o r t i o n that was decanted f r o m the c r u c i b l e , or selective corrosion or fractionation of certain elements o c c u r r e d . T h u s , rather than u n d e r t a k i n g a d e t a i l e d m e t a l l u r g i c a l study, it was d e c i d e d to attempt to p r o v i d e as representative a sample as possible f r o m each s p e c i m e n . T h e heterogeneous mass was d r i l l e d w i t h a carbide b u r r from as m a n y facets of the fragment as possible. H a r d n e s s i n h i b i t e d d r i l l i n g b e y o n d approximately 5 m m from the surface. I n one case, (sample 1010) sufficient identifiable c r u c i b l e was a d h e r i n g to the m e t a l to a l l o w the s a m p l i n g of w h a t c o u l d be representative c e r a m i c .


202


T h e data from this sample w e r e later u s e d to estimate the a m o u n t of c e r a m i c i n each " m e t a l " sample (Table I). T h i s estimation was d o n e b y a s s u m i n g a constant c o m p o s i t i o n for the c e r a m i c c o m p o n e n t (mostly S i , A l , K , M g , a n d Na) a n d b y a s s u m i n g that a l l of the s i l i c o n i n the composite was t h e r e b y v i r t u e of c e r a m i c c o n t a m i n a t i o n . T h u s , the total " c e r a m i c " c o u l d b e s u b tracted, a n d the r e m a i n d e r c o u l d be assumed to b e " m e t a l " . T h i s process is not precise, b u t it d i d seem to account for the b u l k of the A l , N a , K , a n d M g i n the samples. A l l e l e m e n t a l concentrations i n this study w e r e m e a s u r e d b y u s i n g the comparator f o r m o f I N A A , i n w h i c h standards a n d samples are subjected to the same conditions of i r r a d i a t i o n , decay, a n d c o u n t i n g . T h i s m e t h o d m i n i m i z e s the errors d u e to geometry, flux gradients, detector efficiency, etc. T h i s approach was v a l i d a t e d b y e m p l o y i n g standards s i m i l a r i n p h y s i c a l a n d c h e m i c a l c o m p o s i t i o n to the samples. N a t i o n a l B u r e a u o f Standards ( N B S ) standard reference materials ( S R M s ) ( 3 7 E , sheet brass; 872, p h o s p h o r b r o n z e ; 158A, s i l i c o n b r o n z e ; a n d 1633, coal fly ash) w e r e u s e d i n d u p l i c a t e . T w o irradiations w e r e m a d e at different flux, decay, a n d c o u n t i n g t i m e s . V e r y s m a l l p o l y e t h y l e n e vials (0.1-mL) w e r e u s e d to m a i n t a i n good g e o m e t r i c reproducibility. To address a c o n c e r n that there m i g h t b e substantial quantities of u n o b s e r v e d e l e m e n t s , the total accountable mass of each sample was c o m p u t e d . O n l y one sample (804) h a d a n accountable mass close to 100%. T h i s mass was calculated w i t h o u t corrections for the possible corrosion of c o p p e r a n d i r o n that contributes oxygen. T h e c o r r o d e d appearance of the sample w o u l d Table I. Elemental Analysis of Sample 1010. 1010 Metal 6- Ceramic (0.214 g)

Element A l (%) As (ppm) A u (ppm) C u (%) F e (%) K(%) L a (ppm) M g (%). M n (%) N a (%) Sb (ppm) Sc (ppm) Si (%) Sn (%) V (ppm) Zr (ppm)

1.9 710 2.0 26 6.8 1.3 14

± ± ± ± ± ± ±

0.2 70 0.04 2 0.7 0.2 2

0.09 0.26 82 3.7 2.9 12 66 66

± ± ± ± ± ± ± ±

0.01 0.02 10 0.5 0.4 2 8 9

l

Ceramic (0.083 g) 8.4 ± 0.07 15 ± 4

7.0 1.5 54 1.3 0.2 0.20

± ± ± ± ± ±

1 0.2 4 0.4 0.02 0.02

16 ± 2 12 ± 1 150 ± 20 250 ± 20

1010 Metal (0.198 g) 0

0.6 770 2.2 29 7.3

± ± ± ± ±

0.07 70 0.04 2 0.8

15 ± 2 0.1 ± 0.01 90 ± 9 4.0 ± 0.5 13 ± 2 71 ± 9 71 ± 10

NOTE: All values are ± 1σ. (Errors based on a single analysis.) "Corrected eliminating "ceramic" contribution.


10.


203

Metal Residues: INAA

warrant such a c o r r e c t i o n . Perhaps the anomaly was caused b y over-cor r e c t i n g for c e r a m i c c o n t a m i n a t i o n . I n a l l the other cases, this s u m m a t i o n failed to total 100%, so an I N A A p r e d i c t i o n p r o g r a m d e v e l o p e d at the U n i versity of C a l i f o r n i a - I r v i n e ( U C I ) (18) was u s e d to to h e l p e l i m i n a t e possible additional components. T h e analytical methods c o u l d not exclude the p r e s ence of substantial l e a d , n i c k e l , or sulfur, b u t w o u l d exclude s i l v e r , c a l c i u m , cobalt, c h r o m i u m , t i t a n i u m , or z i n c , as s h o w n i n Table I I .

Experimental Procedure Material (50-500 mg) was removed from each specimen by drilling small holes (5 mm deep) at various locations on each sample. Carbide drills were used to to minimize contamination. The sample drillings were collected on weighing paper. Polyethylene vials (2.66 mm high X 9.4 mm o.d., Type-Η container, Biologisch Laboratorium, Vrije Universiteit, Amsterdam) were cleaned with nitric acid followed by three deionized water rinses and a warm air dry. Samples were transferred into the preweighed clean vials with a Teflon [poly(tetrafluoroethylene)]-coated spatula. The vials were subsequently handled only with forceps or plastic-gloved hands. A n iron-coated tipped soldering iron was used to heat-seal the vials. The drill bit and the spatula were rinsed after each sample to prevent sample-to-sample contamination. A n empty vial (cleaned, labeled, and sealed as if it contained sample) was processed in parallel. Portions (100-400-mg) of several different N B S SRMs were similarly encapsulated and analyzed with each group of samples. A small section of gold-doped aluminum wire (Reactor Experiments, Inc., San Carlos, CA), certified as 0.11% gold, was used as a gold standard. Two series of irradiations were made with the U C I 250-kW T R I G A Mark I reactor. The first run consisted of irradiation for 30 s at a thermal neutron flux of 4.8 Χ 10 neutrons c m s using the facility's pneumatic transfer system. Samples were permitted to decay for 1 min and then counted for 2 min on a G e - L i detector (21% efficiency) at a distance of 1.3 cm from the crystal and a gain setting of 0.8 keV per channel. Elements determined in this run were A l , M g , M n , S i , Sn, V, and Zr. 9

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Table II. Lower Limits of Detection (Sample 1006, 0.167 g) Element

Energy (KeV)

W

Ag Ca CI Co Cr Ni Pb Rb S Sr Ti Zn

633 3084.4 2166.8 1173.2 320 1481.7 569.7 1076.6 3102.4 514 320.1 1115.4

2.42 min 8.72 min 37.2 min 5.27 years 27.7 days 2.5 h 0.7 s 18.6 days 5.05 min 64.8 days 5.76 min 243.8 days

Concentration (M) 16 6900 650 0.7 24 2.6 X 10 3.3 x 10 9.4 3.0 x 10 170 300 22 16

24

5

(%)

Possible Major Component

0.010 4.2 0.390 4.2 x Ι Ο 0.014 100 100 5.6 Χ Ι Ο 100 0.10 0.18 0.013

no no no no no yes yes no yes no no no

Proportion

4

3

"Half-life.


204


The second run consisted of a 10-min irradiation at full power (250 kW) in a thermal neutron flux of 1.2 X 10 c m s with the samples loaded in the facility's rotary specimen rack. Samples were allowed to decay for approximately 6 days. (A shorter decay was tried, but the observed dead time was prohibitive). Counts were made for 30 min each with a different G e - L i detector (11% efficiency), at the same crystal-to-sample distance and gain setting previously described. The concentrations of the remainder of the elements were determined as a result of this irradiation. 12

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Discussion of Results T h e e l e m e n t a l concentrations d e t e r m i n e d i n the " m e t a l l i c p h a s e " are g i v e n i n T a b l e I I I . T h e crudeness of the " c e r a m i c c o r r e c t i o n " m e t h o d just d e s c r i b e d adds a d d i t i o n a l u n c e r t a i n t y to some of these values (especially a l u m i n u m , manganese, a n d vanadium). M o s t values, h o w e v e r , are q u i t e m e a n i n g f u l . T h e appreciable i r o n content is expected i f substantial flux r e s i d u e r e mains i n the slag, as has b e e n o b s e r v e d elsewhere (19). T h e h i g h g o l d concentrations seen i n m a n y samples w e r e the most u n e x p e c t e d . Because the samples are d a t e d to the t i m e of the postulated change i n t i n trade routes, a n d therefore t i n source, it is t e m p t i n g to suggest that the g o l d concentration values p r o v i d e a valuable c l u e . T h e " a c c e p t e d " trade route i n the M i d d l e to L a t e B r o n z e A g e s e r v i n g this part of the w o r l d o r i g i n a t e d i n C o r n w a l l , E n g l a n d (20-21). T a b l e I V compares o u r data w i t h data r e p o r t e d b y R a p p (22) f r o m analysis of smelts of C o r n w a l l t i n . T h e discrepancy b e t w e e n these data suggests e i t h e r a different source of t i n or a l i n k b e t w e e n gold a n d an e l e m e n t other than t i n . H o w e v e r , R a p p obtained his data f r o m C o r n i s h ores s m e l t e d i n the present a n d not i n ancient t i m e . E v i d e n c e p r e s e n t e d b y G a l e (23) u s i n g lead isotope data indicates a change i n C r e t e ' s source of c o p p e r b y the L a t e B r o n z e A g e . T h e p r o x i m i t y of D a n to C r e t e , as w e l l as the established parallels i n t h e i r trade routes, m a y b e significant. G a l e postulates a s w i t c h for the source of c o p p e r f r o m C y p r u s to the L a u r i o n i n G r e e c e . I f a change i n t i n source is the cause of this u n u s u a l e l e m e n t a l p a t t e r n (gold i n particular), it w o u l d b e i m p o r t a n t to investigate the r e c e n t l y located s i l v e r a n d gold m i n e i n the Taurus m o u n t a i n s i n T u r k e y , w h i c h has b e e n r e p o r t e d to contain some t i n (24). A l s o m e r i t i n g f u r t h e r i n q u i r y are the e l e m e n t a l concentrations i n metals dating to the B r o n z e A g e a n d f o u n d o n the s h i p w r e c k off C a p e G a l i d o n y a (25). A l t h o u g h absolute i n t e r p r e t a t i o n is risky, further examination of this data indicates a n u m b e r of r o u g h correlations. T h e first is the p a r a l l e l b e t w e e n arsenic a n d gold concentrations ( F i g u r e 1). Table V lists a l l of the samples analyzed along w i t h t h e i r ratios of gold to other elements. E x a m i nation of the arsenic-to-gold ratios indicates that use of this ratio as a c r i t e r i o n w o u l d group m a n y of these samples together, w i t h most falling i n the range of 2 5 0 - 4 0 0 : 1 (As:Au). T h e fact that not a l l of the samples fall w i t h i n this range, is not s u r p r i s i n g because there is no reason to expect that a l l of the excavated samples h a d the same source. S o m e samples may e v e n have o r i g i n a t e d f r o m r e m e l t i n g o l d e r cast objects, a c o m m o n practice.



Al (%) As (ppm) Au (ppm) Cu (%) Fe (%) La (ppm) Mn (%) Sb (ppm) Se (ppm) Sn (%) V (ppm) Zr (ppm) 0(%) Total (%)

Element

1006 0.167 (g) 0.5 ± 0.004 1700 ± 200 6.9± 0.1 28 ± 2 20 ± 2 21 ± 3 0.2 ± 0.02 180 ± 20 7.2 ± 0.8 5.5 ± 0.9 110 ± 10 64 ± 10 16 77 ± 5

-

-

-

-

Table I I I . Elements Observed in 15 Samples of Residues 1015 802 1014 1011 0.074 (g) 0.295 (g) 0.052 (g) 0.475 (g) 0.2 ± 0.003 0.9 ± 0.01 0.2 ± 0.002 1700 ± 200 690 ± 70 1900 ± 200 2200 ± 200 4.8 ± 0.1 0.4 ± 0.01 14 ± 0.2 8.8 ± 0.1 33 ± 4 12 ± 1 35 ± 4 54 ± 2 16 ± 2 22 ± 2 0.6 ± 0.1 64 ± 5 21 ± 2 0.2 ± 0.02 0.5 ± 0.05 0.04 ± 0.01 130 ± 10 38 ± 4 340 ± 30 270 ± 30 18 ± 2 7.7 ± 0.8 7.9 ± 1 1.1 ± 0.2 7 ± 1 1.5 ± 0.4 7.9 ± 2 2.1 ± 0.4 200 ± 30 97 ± 10 110 ± 20 39 ± 5 240 ± 20 75 ± 7 50 ± 20 15 13 9 14 72 ± 7 50 ± 5 52 ± 5 70.5 ± 2

1010 0.198 (g) 0.6 ± 0.07 770 ± 70 2.2 ± 0.04 29 ± 2 7.3 ± 1 15 ± 2 0.1 ± 0.01 90 ± 9 4.0 ± 0.5 13 ± 2 71 ± 9 71 ± 10 10 60 ± 5

-

620 1.8 42 4.3 7 0.03 54 2.3 4.1 110 19

-

806 0.274 (g) ± 60 ± 0.1 ± 2 ± 0.6 ± 2 ± 0.01 ± 5 ± 0.4 ± 0.7 ± 10 ± 7 13 102 ± 7 63 ± 3 Continued on next page.

804 0.061 (g) 0.2 ± 0.002 2200 ± 200 7.5 ± 0.1 64 ± 4 5.8 ± 1 44 ± 5 0.2 ± 0.02 290 ± 30 13 ± 2 32 ± 2 220 ± 30 150 ± 20


± 0.003 ± 200 ± 0.1 ± 2 ± 2 ± 2 ± 0.1 ± 10 ± 0.8 ± 0.8 ± 20 ± 10 15 66 ± 5

0.5 1700 1.8 25 20 28 1.0 130 6.1 4.5 140 93

3

± 0.004 ± 70 ±0.1 ± 2 ± 2 ± 2 ± 0.01 ± 10 ± 0.8 ± 0.9 ± 10 ± 10 14 69 ± 5

0.6 750 0.3 21 20 25 0.05 120 7.8 14 99 82

808 0.193 (g) ± 0.003 ± 200 ±0.1 ± 3 ± 3 ± 3 ± 0.1 ± 8 ± 0.9 ± 1 ± 20 ± 10 19 85 ± 6

o.ui (g) 0.3 1700 0.8 36 22 17 0.5 85 4.4 7.2 160 72

809 ± ± ± ±

0.01 200 0.1 4

82 ± 10 21 ± 10 17 91 ± 5

110 ± 10 5.4 ± 1

0.4 1600 12 68

1003 0.117(g) ± 0.004 ± 100 ± 0.1 ± 2 ± 0.9 ± 2 ± 0.001 ± 9 ± 0.8 ± 2 ± 10 ± 9 7 41 ± 5

0.5 1300 3.1 16 6.0 23 0.1 95 7.9 12 170 83

1004 0.169(g)

82

210 1.3 3.2 30

0.4 2800 60 62 0.6

± 0.01 ± 300 ± 0.3 ± 3 ± 0.2 _ _ ± 20 ± 0.2 ± 0.6 ± 5 _ 16 ± 3

b

1012 0.301 (g) (metal)

b

2

NOTE: Column headings are sample numbers. A l l values are ± 1σ (errors based on a single analysis). Values not detected indicated by "Assuming pure C u O and F e 0 . Metal fragment samples, no ceramic correction applied.

A l (%) ' As (ppm) A u (ppm) C u (%) Fe (%) L a (ppm) M n (%) Sb (ppm) Sc (ppm) Sn (%) V (ppm) Zr (ppm) 0(%) Total (%)

Element

807 0.163 (gj

Table III. Continued

± 0.01 ± 1000 ± 0.1 ± 3 _ _

39 ± 6 _ 18 91 ± 3

-

480 ± 50 _

0.6 12000 14 71

h

1013 0.200(g) (metal)

3

Η g

Ο

r

ο >

r ο ο

>

S3 m Ο

>

1

10.

M A N E A - K R I C H T E N ET AL.

207


Table IV. Trace Element Concentrations i n Cassiterite (Sn0 ) Smelts from Cornwall, England, Deposits and Mean Values Obtained i n Residues from Tel D a n , Israel 2

Element

Cornwall

Tel Dan (ppm)

(ppm)

9 0.11 66 1000 9 670 20 39 2 15

Ag Au Cr Fe Hg Ni Ru Se Ta W

—

9.2

-

121,000

_

-

SOURCE. Adapted from reference 22. NOTE: - indicates not detected.

120

υ 1013

I

1

1

ι

I

90

m

Ο

ε

Ω.

60

QL

< 30 I0I2

ο

10

ι

»

I

20

30

40

I 50

C

60

Au(ppm) Figure 1. Correlation

plot of gold relative to arsenic

concentration.

C o r r e l a t i o n of the t i n - t o - g o l d a n d copper-to-gold concentrations is not as good (Figures 2 a n d 3). T h i s result may indicate that the arsenic, rather than t i n or c o p p e r , was the source of the g o l d i n the r e s i d u e (assuming that h i g h arsenical c o p p e r ore was not used i n this period). T h i s i d e a seems to b e s u p p o r t e d b y the degree of correlation f o u n d b e t w e e n the a n t i m o n y a n d gold values ( F i g u r e 4). Ratios of 2 5 - 4 0 : 1 (Sb:Au) are seen for the c o r r e l a t e d group. M o s t l i k e l y , a n t i m o n y w o u l d enter as an i m p u r i t y w i t h a d d e d arsenic along w i t h m u c h of the gold. H o w e v e r , d u r i n g h i g h - t e m p e r a t u r e w o r k i n g , m u c h arsenic is c o m m o n l y lost because of the l o w s u b l i m a t i o n t e m p e r a t u r e of the m e t a l a n d its c o m p o u n d s relative to a n t i m o n y . P e r h a p s at the t e r n -



Ratio

5

13

4.1

41

26

0.8

360

1010

250

1006

7

1.4

26

360

1011

32

3.3

95

1900

1014

2.5

0.6

25

140

1015

6.1

0.2

30

260

802

8.6

5

38

300

804

23

2.5

30

340

806

14

2.5

72

950

807

80

2.5

410

2900

808

44

50

110

2040

809

6

10

9

130

1003

5

0.4

30

420

1004

1

3.3

4

50

1012

5

0.1

34

850

1013

NOTE:

Column headings are sample numbers. All samples were residues except 1012 and 1013, which were metals. All samples were from Tel Dan except 1003 and 1004, which were from Tel Akko.

As ; A u (ppm:ppm) Sb : A u (%:ppm) Sn : A u (%:ppm) Cu: Au (%:ppm)

Table V. Ratios of Elements Determined i n Samples Analyzed

10.

M A N E A - K R I C H T E N ET AL.

209


Figure 2 . Correlation plot of gold relative to tin

Figure 3. Correlation plot of gold relative to copper

concentration.

concentration.

peratures r e a c h e d w h e n these materials w e r e w o r k e d an e q u i l i b r i u m was possible that l e d to a relatively stable arsenic concentration i n the residues. S a m p l e 1013 is a c o r r o d e d piece of m e t a l that s h o w e d no c e r a m i c c o n tamination (macroscopically or chemically) a n d contained n o detectable t i n . If this w e r e a c o p p e r ingot, or p i n r e s u l t i n g from the m e l t i n g of a p l a i n



210

720

Figure 4. Correlation plot of gold relative to antimony concentration.

c o p p e r ingot, the h i g h g o l d , arsenic, a n d a n t i m o n y concentrations (despite the lack of tin), w o u l d strengthen the i d e a that the g o l d content is not r e l a t e d to the t i n content a n d therefore cannot be u s e d to infer a change i n t i n source. T h e h i g h l e v e l o f arsenic seen i n these samples a n d i n the L a u r i o n samples (23), i n forms i n w h i c h it may have b e e n i n c o r p o r a t e d into c o p p e r m e t a l , indicates c o p p e r , rather t h a n t i n , as the a l l o y i n g m e t a l source most responsible for the u n u s u a l data observed. A m u c h s m a l l e r a m o u n t o f g o l d c o u l d have b e e n a characteristic of the t i n , b u t it w o u l d have b e e n m a s k e d b y the h i g h e r concentration apparently r e s i d i n g w i t h the a r s e n i c - c o p p e r component.

Conclusion T h e o v e r a l l data may not b e u s e d i n such an absolute sense as i n analysis o f a b r o n z e casting, b u t they do p r o v i d e some i n t e r e s t i n g i n f o r m a t i o n . S u b stantial concentrations of g o l d a n d arsenic w e r e o b s e r v e d that appear to correlate w i t h one another a n d w i t h a n t i m o n y concentration. F u r t h e r w o r k is n e e d e d to find authentic sources of the copper, t i n , fluxes, a n d other materials u s e d at these sites. A p p a r e n t l y , m e a s u r e m e n t of gold c o n c e n t r a tions cannot b e u s e d to answer questions about a change i n the sources of t i n d u r i n g this p e r i o d . E x a m i n a t i o n of these samples to d e t e r m i n e a d d i t i o n a l trace e l e m e n t concentrations continues. F u r t h e r examination of the nature of the c e r a m i c materials is p r o c e e d i n g .


10.



211

Acknowledgment W e are grateful to A v r a h a m B i r a n from the H e b r e w U n i o n C o l l e g e i n J e r u s a l e m w h o , as director of excavations at T e l D a n , granted p e r m i s s i o n to r e m o v e a n d analyze these materials. W e also thank M o s h e D o t h a n of H a i f a U n i v e r s i t y , D i r e c t o r of Excavations at T e l A k k o for p e r m i s s i o n to r e m o v e and analyze materials. T h i s w o r k was s u p p o r t e d , i n part, b y a Reactor S h a r i n g grant p r o v i d e d b y the U . S . D e p a r t m e n t of E n e r g y to U C I .

References 1. Jacobs, J . W.; Korotev, R. L.; Blanchard, D . P.; Haskin, L . A. J. Radioanal. Chem. 1977, 40, 93-114. 2. Maddin, R.; Wheeler, T. S.; M u h l y , J . D . Expedition 1977, 19(2), 35. 3. M u h l y , J . D . Am. Sci. 1973, 66, 404. 4. Goffer, Z. Archaeological Chemistry; Wiley: New York, 1980; p 200. 5. Wertime, T. A . In The Search For Ancient Tin; Franklin, A . D . ; Olin, J . S.; Wertime, Τ. Α., E d s . ; Smithsonian Institution: Washington, D C , 1977; p 1. 6. Heidebrecht, N., P h . D . Thesis, University of California at Los Angeles, to be submitted. 7. Heidebrecht, N . Presented at the American Oriental Society Meeting, Univer sity of Michigan; A n n Arbor, M I , 1985. 8. Tylecote, R. F. A History of Metallurgy; The Metals Society: London, 1976. 9. Tylecote, R. F.; L u p u , Α.; Rothenberg, B. J. Inst. Metals 1967, 95, 235. 10. Mazar, B. Isr. Exploration J. 1950-1951, 1, 123; 7, 265; 8, 180. 11. Tylecote, R. F. The Prehistory of Metallurgy in the British Isles; The Institute of Metals; London, 1986. 12. Tylecote, R. F. In Archeological Ceramics; Olin, J . S.; Franklin, A . D . , E d s . ; Smithsonian Institution: Washington, D C , 1982; 231-242. 13. Craddock, P. Α., personal communication. 14. Charles, J . A . In The Search For Ancient Tin; Franklin, A . D . ; O l i n , J . S.; Wertime, T. S., E d s . ; Smithsonian Institution: Washington, D C , 1977; p 25. 15. Charles, J. A . Antiquity 1975, 49, 19. 16. Schuiling, R. D . Econ. Geol. 1967, 62, 540. 17. Heltzer, M. Goods, Prices, and The Organization of Trade in Ugarit; Reichert: Weisbaden, 1978. 18. Crofoot, T. A . ; , Miller, G . E . Spreadsheet Programs for Neutron Activation Analysis; to be published. 19. Tylecote, R. F. In Aspects of Early Metallurgy; Oddy, W. Α., E d . ; British Museum Occasional Paper No. 17, 1980. 20. M c K e r r e l l , H . In The Search For Ancient Tin; Franklin, A . D . ; Olin, J . S.; Wertime, Τ. Α., E d s . ; Smithsonian Institution: Washington, D C , 1977; p 7. 21. Tylecote, R. F. In The Search For Ancient Tin; Franklin, A . D . ; Olin, J . S.; Wertime, Τ. Α., E d s . ; Smithsonian Institution: Washington, D C , 1977; p. 49 22. Rapp, G . In The Search for Ancient Tin; Franklin, A . D . ; O l i n , J . S.; Wertime, Τ. Α., Eds.; Smithsonian Institution: Washington, D C , 1977; p 59. 23. Gale, N. H.; Stos-Gale, Z. A . Science, 1982, 216, 11. 24. Yener, K. A . Presented at the 196th Meeting of the American Oriental Society, New Haven, C T , March 1986. 25. Bass, G . Trans. Am. Phil. Soc. - New Series 1967 57 part 8, 44. RECEIVED for review June 11, 1987. ACCEPTED revised manuscript March 29, 1988.


Instrumental Neutron Activation Analyses of Metal Residues

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