Archaeological Chemistrypubs.acs.org/doi/pdf/10.1021/ba-1974-0138.ch013SimilarChemistry Department, Brooklyn College, Ci...
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13 Chemical Investigations of Ancient Near
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Eastern Archaeological Ivory Artifacts N. S. BAER Conservation Center, Institute of Fine Arts, New York University, 1 East 78th St., New York, Ν. Y. 10021 N. INDICTOR Chemistry Department, Brooklyn College, City University of New York, Brooklyn, Ν. Y. 11210
The composition of buried bone changes with time. Hydroxyapatite, the major inorganic component, undergoes very slow exchange with ionic species from groundwaters. The nitrogen content decreases as the collagenous material is removed and replaced, in part, by inorganic salts. The rate of nitrogen loss is generally much greater than the rate of the exchange reaction. The results of carbon, hydrogen, nitrogen, and ash analyses for samples of ivory excavated in the Ancient Near East reveal a similar compositional varia tion. In excavated specimens of known provenance (Hasanlu, Northwest Iran; Nimrud, Iraq; and Acem Hüyük, Anatolia) the nitrogen content was ≤0.5% (except for black ivories from Hasanlu) whereas the nitrogen content of modern elephant ivory is > 5.0%. The percent ash, as combustion residue, was > 80% for excavated ivory compared with ca. 55% for modern elephant ivory. The generality of these results for many samples has suggested the use of these data to develop criteria for the chemical examination of artifacts of doubtful provenance.
A rtifacts a n d w o r k s of a r t h a v e b e e n c a r v e d f r o m b o n e a n d i v o r y f r o m p r e h i s t o r i c times. T h e i m p o r t a n c e of these objects to art h i s t o r i c a l s c h o l a r s h i p is w e l l d o c u m e n t e d .
I n recent years, m a n y i v o r y artifacts
h a v e b e e n r e c o v e r e d i n excavations i n t h e A n c i e n t N e a r E a s t f r o m s u c h 236
Beck; Archaeological Chemistry Advances in Chemistry; American Chemical Society: Washington, DC, 1974.
13.
237
IVOTtf Artifacts
B A E R A N D INDICTOR
sites as N i m r u d , H a s a n l u , A c e m H i i y i i k , a n d K h o r s a b a d . T h e s e c a r v i n g s have attracted considerable (1, 2, 3, 4, 5).
art historical a n d archaeological
attention
T h e e x c a v a t e d ivories r a n g e f r o m w h i t e t h r o u g h b r o w n ,
grey, b l u e a n d b l a c k .
T h e m e c h a n i s m o f color f o r m a t i o n b y t h e a c t i o n
of h i g h t e m p e r a t u r e has b e e n d e s c r i b e d (6,7).
I n this p a p e r t h e q u e s t i o n
of a u t h e n t i c i t y is c o n s i d e r e d f o r ivories of u n k n o w n p r o v e n a n c e s a i d to be f r o m t h e A n c i e n t N e a r E a s t . Downloaded by NANYANG TECHNOLOGICAL UNIV on September 23, 2017 | http://pubs.acs.org Publication Date: June 1, 1974 | doi: 10.1021/ba-1974-0138.ch013
I n 1958 the M e t r o p o l i t a n M u s e u m of A r t p u r c h a s e d a g r o u p of i v o r i e s s a i d to b e f r o m K h o r s a b a d , a n c i e n t D u r S a r r u k i n , t h e u n f i n i s h e d c a p i t a l b u i l t ( 7 1 3 - 7 0 7 B . C . ) f o r K i n g S a r g o n ( S a r r u k i n ) of A s s y r i a (2,8).
Con
s i d e r a b l e difference of o p i n i o n exists a m o n g art historians a n d archeaeologists as to the assignment of these ivories to K h o r s a b a d . T h e r e is also some q u e s t i o n of t h e i r a u t h e n t i c i t y as a n c i e n t A s s y r i a n ivories. C h e m i c a l m e t h o d s of d a t i n g h a v e b e e n a p p l i e d to p r e h i s t o r i c b o n e specimens w i t h v a r y i n g degrees of success (9, 10).
T h e most
notable
e x a m p l e is the case of t h e P i l t d o w n forgeries i n w h i c h m a n y a n a l y t i c a l methods w e r e u s e d (11, 12).
T h e f l u o r i d e exchange m e t h o d , o r i g i n a l l y
p r o p o s e d i n the last c e n t u r y (13, 14) w a s r e i n t r o d u c e d f o r this p r o b l e m b y O a k l e y a n d has since f o u n d w i d e a p p l i c a t i o n f o r e x c a v a t e d b o n e . T h e m e t h o d d e p e n d s o n t h e g r a d u a l a c c u m u l a t i o n b y t h e s p e c i m e n of from groundwaters.
fluoride
O t h e r systematic changes s u c h as t h e v a r i a t i o n of
u r a n i u m , carbonate, n i t r o g e n , a n d p h o s p h o r u s content h a v e b e e n u s e d i n conjunction w i t h
fluoride
data.
T h e carbon-14 m e t h o d has b e e n
used
w i t h s o m e success u n d e r s p e c i a l c i r c u m s t a n c e s ( 1 5 , 16).
F o r the past 25
years, c h e m i c a l analysis of b o n e f o r d a t i n g purposes
has f o c u s e d
on
changes i n t h e proteinaceous m a t e r i a l . I n this w o r k , w e h a v e s t u d i e d the change i n c o l l a g e n content, b y e l e m e n t a l analyses, f o r b u r i e d i v o r y o b t a i n e d f r o m a r c h a e o l o g i c a l e x c a v a tions. T h e sites m e n t i o n e d i n this s t u d y are g i v e n i n T a b l e I . T h e results of t h e analyses f o r e x c a v a t e d specimens
are c o m p a r e d
w i t h those f o r
ivories of u n k n o w n p r o v e n a n c e . Experimental Sample Preparation. S a m p l e s f r o m objects w e r e o b t a i n e d b y d r i l l i n g d e e p l y ( ca. 2 c m ) i n t o the object, d i s c a r d i n g t h e i n i t i a l s u p e r f i c i a l m a t e r i a l . T h e a m o u n t of useable s a m p l e o b t a i n e d w a s g e n e r a l l y 2 - 3 m g p e r Table I.
Locations of Ancient Near Eastern Archaeological Sites and Period Attributions of Specimens Examined
Site
Period
Hasanlu Acem Huyuk Nimrud Khorsabad
9th century B . C . 19th-18th century B . C . 9th-8th century B . C . 8th century B . C .
Description Northwest Iran, Period I V Anatolia Iraq Ancient D u r Sarrukin, Iraq
Beck; Archaeological Chemistry Advances in Chemistry; American Chemical Society: Washington, DC, 1974.
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ARCHAEOLOGICAL CHEMISTRY
d r i l l i n g . W h e n e x p e n d a b l e fragments w e r e a v a i l a b l e , t h e i r surface w a s c l e a n e d b y m e c h a n i c a l s c r a p i n g of t h e surface w i t h a s c a l p e l . Analyses. A n a l y s e s of a s h , c a r b o n , a n d h y d r o g e n b y c o m b u s t i o n , a n d n i t r o g e n b y D u m a s or m i c r o - K j e l d a h l m e t h o d s (17) w e r e o b t a i n e d f r o m S c h w a r z k o p f M i c r o a n a l y t i c a l L a b o r a t o r y , W o o d s i d e , Ν. Y . 11377. Analytical Errors. E r r o r s associated w i t h these d a t a arise f r o m u n certainties i n the a n a l y t i c a l m e t h o d s a n d f r o m i m p u r i t i e s i n t r o d u c e d into o r present i n the i v o r y m a t r i x . T h e s e a d d e d materials are e i t h e r i n o r g a n i c salts f r o m g r o u n d w a t e r r e p l a c i n g collagenous m a t t e r d u r i n g b u r i a l or o r g a n i c m a t e r i a l u s e d i n the c o n s e r v a t i o n l a b o r a t o r y to i m p r e g n a t e f r i a b l e specimens. T h e u n c e r t a i n t i e s for the a n a l y t i c a l m e t h o d s are as f o l l o w s : ash b y c o m b u s t i o n r e s i d u e , ± 0 . 3 % a b s o l u t e ; C , ± 0 . 0 5 m g C ; H , ± 0 . 3 % abso l u t e ; a n d N , b y D u m a s , ± 5 μ\ or b y m i c r o - K j e l d a h l , ± 1 μg (18). The l a r g e u n c e r t a i n t i e s i n the measurements of c a r b o n a n d h y d r o g e n l i m i t the usefulness of d a t a for these elements for v e r y s m a l l samples. E r r o r s associated w i t h i n o r g a n i c salts arise f r o m the presence of a d d e d c a r b o n a t e a n d n i t r a t e . T h e results of l e a c h i n g experiments w i t h H C 1 to e l i m i n a t e c a r b o n a t e i n d i c a t e the presence of n e g l i g i b l e a d d i t i o n a l c a r b o n a t e (6, 19). T h e use of N 0 " i n s e n s i t i v e m e t h o d s for n i t r o g e n d e m o n s t r a t e d the absence of m e a s u r a b l e nitrates. M e t h o d s for s t r e n g t h e n i n g f r i a b l e i v o r y artifacts are d e s c r i b e d b y P l e n d e r l e i t h a n d W e r n e r (20). T h e m a t e r i a l s u s e d w i l l l e a d to h i g h c a r b o n a n d h i g h h y d r o g e n values g e n e r a l l y a n d h i g h n i t r o g e n values o n l y w h e n n i t r o g e n is a constituent of the i m p r e g n a t i n g material—e.g., s o l u b l e n y l o n , n i t r o c e l l u l o s e , etc. D i s c a r d i n g t h e s u p e r f i c i a l m a t e r i a l tends to e l i m i n a t e this source of error except i n v a c u u m i m p r e g n a t i o n . W h e n the treatment h i s t o r y of a n a r t i f a c t i n d i c a t e s v a c u u m i m p r e g n a t i o n , solvents m a y b e u s e d to l e a c h out the extraneous matter. 8
Discussion Related Materials. T a b l e I I gives the results of e l e m e n t a l analyses f o r b o n e , i v o r y , a n d r e l a t e d specimens.
T h e mastadon, mammoth, and
a n c i e n t w a l r u s s a m p l e analyses i n d i c a t e d r e t a i n e d proteinaceous m a t t e r i n c o m p o s i t i o n e q u i v a l e n t to that for m o d e r n e l e p h a n t i v o r y . T h i s s u g gests t h a t these m a t e r i a l s w o u l d not p r o v i d e a r e a d y source of
"aged"
i v o r y f o r a m o d e r n c a r v e r s e e k i n g to d u p l i c a t e the texture a n d c o m p o s i t i o n of i v o r y b u r i e d for w e l l over 2,000 years. Acem H i i y u k . T h e d a t a i n T a b l e I I I for these, the oldest artifacts e x a m i n e d , r e v e a l a consistent loss of o r g a n i c m a t t e r w i t h n o nitrogen.
detectable
T h i s w o u l d i n d i c a t e a c o m p l e t e loss of proteinaceous m a t t e r
w i t h s o m e r e s i d u a l free c a r b o n . A s p r e v i o u s l y r e p o r t e d (6),
the presence
o f b l u e , b l a c k , or g r e y c o l o r a t i o n i n i v o r y has b e e n a t t r i b u t e d to the t h e r m a l d e c o m p o s i t i o n of the c o l l a g e n w i t h a c o n s e q u e n t d e p o s i t i o n of free c a r b o n . S o m e loosely h e l d w a t e r was o c c a s i o n a l l y present. L e a c h i n g e x p e r i m e n t s ( s a m p l e s m a r k e d A c e m H i i y i i k I V ) d e m o n s t r a t e the p o s s i b l e presence of o n l y a s m a l l a m o u n t of carbonate.
Beck; Archaeological Chemistry Advances in Chemistry; American Chemical Society: Washington, DC, 1974.
13.
BAER A N D i N D i C T O R
Table II.
Carbon, Hydrogen, Nitrogen, and Ash Analyses for Specimens of Ivory and Related Materials
Specimen
%Ash
E l e p h a n t i v o r y (Africa) M a m m o t h tusk ( N . E . Siberia) Mastadon Sperm whale tooth W h a l e bone (rib) Hippopotamus tooth Boar tooth (Aitape, N e w Guinea) Ancient walrus tusk ( A l a s k a ) Beef bone 6
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6
c
d
a b c d
239
Ivory Artifact s
%c
53.32 54.24 56.04 66.02 71.62 60.36 65.57 60.46 68.68
5.52 5.37 5.78 4.23 3.03 4.25 3.86 4.75 3.52
16.25 15.64 16.85 12.28 11.85 12.64 12.25 15.16 10.94
A l l analyses by Dumas method. Pleistocene Epoch, courtesy The American Museum of Natural History. Fossilized specimen, courtesy The American Museum of Natural History. Collagenous material extracted with boiling water for 2 hrs. N i m r u d . T h e samples a n a l y z e d f r o m N i m r u d w e r e a l l w h i t e ( T a b l e
I V ) . I n g e n e r a l , the ash content was a p p r o x i m a t e l y 8 5 % w h i l e the n i t r o g e n content v a r i e d f r o m 0 - 0 . 4 % . again observed,
T h e g e n e r a l loss of o r g a n i c m a t t e r is
t h o u g h a s m a l l a m o u n t of
nitrogenous
m a t e r i a l has
survived. Hasanlu. T h e s e specimens f a l l i n t o t w o d i s t i n c t classes : b l a c k objects a n d objects w h i c h are some shade of grey ( T a b l e V ) . T h e grey objects h a v e c o m p o s i t i o n s not u n l i k e the specimens f r o m N i m r u d ( T a b l e I V ) . H o w e v e r , the b l a c k objects demonstrate a s i g n i f i c a n t l y h i g h e r c o n c e n t r a t i o n of proteinaceous m a t e r i a l . T h e w e l l p r e s e r v e d b l a c k object, H a s a n l u Table III. Analyses and Color of Ancient Ivory Specimens from Acem H i i y i i k , Anatolia (19th-18th Century B.C.) Color
Specimen Acem Acem Acem Acem Acem Acem a b c d e
Huyuk Huyuk Huyuk Huyuk Huyuk Huyuk
I II III IV IV IV
6 0 e
black-grey blue-grey grey-white white white white
%Ash 78.43 92.60 97.34 98.86 98.81 nd
%c 2.65 2.12 0.41 0.38 0.33 0.22
0.76 0.41 0.23 0.09 0.05 nd
0 0 0 0 nd nd
d
A l l anlyses by Dumas method. 20-mg sample. 70-mg sample. No data. After treatment with H CI to remove carbonates.
V , d e s c r i b e d elsewhere ( 4 ) , represents o u r o n l y e x a m p l e of a n e x c a v a t e d i v o r y w i t h a n i t r o g e n content greater t h a n 1 % .
T h e presence of
free
c a r b o n seems to h a v e p r o t e c t e d p a r t i a l l y the c o l l a g e n f r o m the a c t i o n of g r o u n d w a t e r a n d b a c t e r i a . T h i s o b s e r v a t i o n is s u p p o r t e d b y the g e n -
Beck; Archaeological Chemistry Advances in Chemistry; American Chemical Society: Washington, DC, 1974.
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ARCHAEOLOGICAL CHEMISTRY
Table IV. Analyses and Color of Ancient Ivory Specimens from N i m r u d , Iraq (9th-8th Century B.C.) Color
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Specimen Nimrud Nimrud Nimrud Nimrud Nimrud Nimrud Nimrud
I II III IIP IV V V d
white white white white white white white
%
Ash
85.6 82.2 82.3 nd 83.62 87.16 nd c
%c
%H
4.33 4.39 5.45 nd 5.12 2.52 nd
0.86 1.21 1.18 nd 1.04 0.87 nd
%N« 0 0 0.39 0.19 0.25 0.36 0.13
(K)
A l l analyses by Dumas method except when marked (K) for Kjeldahl. 2.5-mg sample. No data. Metropolitan Museum of A r t accession number 59.107.9, fragment.
a 6 0 d
e r a l l y better p r e s e r v e d state of e x c a v a t e d b l a c k i v o r y w h e n w i t h ivories of other color Khorsabad.
compared
(21).
T h e " K h o r s a b a d " i v o r y specimens
examined
s c r i b e d i n T a b l e V I . F i g u r e s 1 a n d 2 s h o w t w o of t h e o b j e c t s — a figure
with bucket and an open-work
griffin.
are
de
winged
A n a l y t i c a l d a t a for their
e l e m e n t a l analyses are p r e s e n t e d i n T a b l e V I I . I n g e n e r a l , a p p r o x i m a t e l y Table V . Analyses and Color of Ancient Ivory Specimens from Hasanlu, Northwest Iran, Period IV (9th Century B.C.) Color
Specimen Hasanlu Hasanlu Hasanlu Hasanlu Hasanlu α b
I II III IV V 6
grey white-grey grey black black
%
Ash
87.15 84.35 87.55 87.48 77.69
%c
%H
2.36 3.11 2.90 4.40 8.52
0.65 0.92 0.63 0.47 1.18
0.53 0.52 0.54 0.95 1.50
(K)
A l l analyses by Dumas method except when marked (K) for Kjeldahl. Metropolitan Museum of A r t accession number 65.163.21.
2 m g of s a m p l e w e r e u s e d i n m a k i n g the analyses. S p e c i m e n I I I , a f r a g m e n t , p e r m i t t e d a greater s a m p l e size. T h e d a t a are c l e a r l y c o m p a r a b l e w i t h those f o r t h e e x c a v a t e d specimens f r o m H a s a n l u a n d N i m r u d .
The
h i g h ash values a n d g e n e r a l l y l o w n i t r o g e n analyses demonstrate a c o n s i d e r a b l e loss of proteinaceous m a t e r i a l . I n T a b l e V I I I , the c o m p o s i t e values for a l l analyses, b y g r o u p , are p r e s e n t e d together w i t h the analyses for m o d e r n e l e p h a n t i v o r y a n d for a n " A s s y r i a n " i v o r y of u n k n o w n p r o v e n a n c e i n a p r i v a t e c o l l e c t i o n .
The
results of the e l e m e n t a l analyses for the K h o r s a b a d ivories are consistent w i t h those for the e x c a v a t e d specimens.
Samples f r o m the A s s y r i a n i v o r y
f r o m the p r i v a t e c o l l e c t i o n , h o w e v e r , y i e l d analyses w h i c h are not c o n -
Beck; Archaeological Chemistry Advances in Chemistry; American Chemical Society: Washington, DC, 1974.
13.
BAER A N D i N D i C T O R
Table V I .
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a
I II III IV V
241
Artifacts
Designations of " K h o r s a b a d " Ivory Specimens (Provenance Unknown) Accession
Specimen Khorsabad Khorsabad Khorsabad Khorsabad Khorsabad
Ivory
Number"
58.122.7 58.122.1-11 58.122.1-11 58.122.10 58.122.11
Description w i n g e d figure w i t h b u c k e t drilling from fragment chip from fragment griffin, s t r i d i n g o p e n w o r k lion, carved i n the round
Metropolitan Museum of Art.
Figure 1. Open work ivory plaque, standing winged figure with bucket. Height, 15.5 cm; width, 7.9 cm. Metropolitan Museum of Art accession number 58.122.7. Reputedly from Khorsabad.
Beck; Archaeological Chemistry Advances in Chemistry; American Chemical Society: Washington, DC, 1974.
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242
ARCHAEOLOGICAL CHEMISTRY
Figure 2. Open work striding griffin, deco rated on both sides. Height, 5.4 cm; width, 10.3 cm. Metropolitan Museum of Art acces sion number 58.122.10. Reputedly from Khorsabad. Table VII.
Analyses and Color of " K h o r s a b a d " Ivory Specimens (Provenance Unknown)
Specimen
Color
Khorsabad Khorsabad Khorsabad Khorsabad Khorsabad α b
I II III IV V
%
Ash
4.1 nd 5.2 5.6 2.9
90.4 nd" 84.2 83.3 81.8
white white white white white
%H
%c
1.5 nd 1.1 0(?) 1.4
%N' 0.5 0.4 0.2 0.5 0.4
(K) (K) (K) (K)
Analysis by Dumas method where not marked (K) for Kjeldahl. No data. Table VIII. Comparison of Composite Values for Analyses of Excavated Ancient Near Eastern Ivory Specimens with Specimens of U n k n o w n Provenance 0
Specimen
Date
Color
modern
Elephant Ivory Nimrud Hasanlu Hasanlu Acem Huyuk Khorsabad Assyrian c
6
9th-8th century 9th century 9th century 19th-18th century unknown unknown
%Ash
w h i t e 53.32 (3) B.C.
16.25 (3) 3.52 (3) 5.52 (3)
w h i t e 84.2
(5)
4.36 (5)
86.4
(3)
2.78 (3) 0.73 (3) 0.53 (3)
b l a c k 82.6
(2)
6.46 (2) 0.83 (2)
grey B.C. B.C. B.C.
%N
%c
w h i t e 91.94 (6) w h i t e 84.9 w h i t e 60.7
(4) (2)
1.03 (5) 0.19 (7)
1.23 (2)
1.02 (6) 0.31 (5) 0
(4)
4.4 (4) 1.0 .(4) 0.4 (5) 10.83 (2) 2.77 (2) 3.65 (2)
Composite value refers to the average of all sample analyses. Number of analyses appears in parentheses. See Table V I for description of specimens. Object of uncertain provenance in private collection. α
b c
Beck; Archaeological Chemistry Advances in Chemistry; American Chemical Society: Washington, DC, 1974.
13.
BAER A N D i N D i C T O R
Ivory
243
Artifacts
sistent w i t h those for A n c i e n t N e a r E a s t e r n i v o r i e s , thus far a n a l y z e d , of k n o w n provenance. Conclusions Elemental Analyses.
T h e d a t a for samples o b t a i n e d f r o m i v o r i e s
e x c a v a t e d at three A n c i e n t N e a r E a s t e r n sites ( N i m r u d , A c e m H u y u k , Downloaded by NANYANG TECHNOLOGICAL UNIV on September 23, 2017 | http://pubs.acs.org Publication Date: June 1, 1974 | doi: 10.1021/ba-1974-0138.ch013
H a s a n l u ) demonstrate a u n i f o r m b e h a v i o r s i m i l a r to t h a t of b u r i e d b o n e . T h e f u n d a m e n t a l c h a n g e is the decrease i n n i t r o g e n content as this c o l lagenous m a t e r i a l is r e m o v e d a n d r e p l a c e d , i n p a r t , b y i n o r g a n i c salts. I n this study, the n i t r o g e n content was <
0 . 5 % , except for t h e b l a c k
ivories f r o m H a s a n l u whereas the n i t r o g e n content for m o d e r n e l e p h a n t i v o r y is >
5.0%.
T h e p e r c e n t ash, as c o m b u s t i o n r e s i d u e , w a s >
80%
for e x c a v a t e d i v o r y vs. ca. 5 5 % for m o d e r n e l e p h a n t i v o r y . T h e l i m i t e d scope of this s t u d y m u s t be e x p a n d e d to i n c l u d e a d d i t i o n a l sites, m o r e b l a c k i v o r i e s , a n d a greater s a m p l e u n i v e r s e b e f o r e s u c h a n a l y t i c a l d a t a m a y be a p p l i e d w i t h confidence ivories of u n k n o w n p r o v e n a n c e .
as c r i t e r i a for the a u t h e n t i c a t i o n of F u r t h e r w o r k is also n e e d e d to c h a r a c
terize m o r e t h o r o u g h l y the changes i n c o m p o s i t i o n a c c o m p a n y i n g b o t h n a t u r a l a n d artificial a g i n g of i v o r y . Additional Methods of Analysis. S e v e r a l methods of analysis, other t h a n those r e p o r t e d a b o v e , h a v e b e e n u s e d w i t h v a r y i n g success to the r e l a t i v e d a t i n g a n d , i n some cases, to the absolute d a t i n g of b o n e .
The
l i m i t e d amounts of s a m p l e a v a i l a b l e for analysis, t y p i c a l l y o n the o r d e r of a f e w m i l l i g r a m s , c u r r e n t l y p r e c l u d e r a d i o c a r b o n a n d t h e r m o l u m i nescence d a t i n g . T w o other exchange processes o b s e r v e d i n b u r i e d b o n e ; F~ e x c h a n g e w i t h O H " to f o r m
fluorapatite,
a n d the exchange of u r a n i u m
for c a l c i u m i n the apatite lattice, s h o u l d be c o n s i d e r e d .
T h o u g h these
processes are far m o r e c h a r a c t e r i s t i c of the specific a r c h e o l o g i c a l site t h a n is c o l l a g e n loss, t h e y s h o u l d p r o v i d e v a l u a b l e i n f o r m a t i o n s u p p l e m e n t i n g the changes
i n the o r g a n i c components
of i v o r y .
Preliminary
fluoride
analyses o n e x c a v a t e d ivories i n d i c a t e c o n s i d e r a b l e p r o m i s e for a r c h a e o l o g i c a l sites w h i l e others a p p e a r to b e insensitive
some
(22).
T h e c r i t i c a l p r o b l e m of s a m p l e size a n d the l i m i t a t i o n s i m p o s e d t h e r e b y o n the a c c u r a c y of e l e m e n t a l analyses, e s p e c i a l l y those for c a r b o n a n d h y d r o g e n , suggest the a p p l i c a t i o n of c h r o m a t o g r a p h i c
techniques.
A m i n o a c i d analysis m a y p r o v i d e a s u p e r i o r m e t h o d of assessing c o l l a g e n loss w i t h a d d i t i o n a l i n f o r m a t i o n r e g a r d i n g t h e selective
decomposition
processes, sensitive to l o c a l s o i l c o n d i t i o n s . Ivories of U n k n o w n Provenance. T h e d a t a for the K h o r s a b a d ivories are consistent w i t h the suggested
age.
T h e s e d a t a d o not,
however,
e l i m i n a t e the p o s s i b i l i t y of a r t i f i c i a l m e t h o d s for s i m u l a t i n g t h e p a t i n a a n d texture, g e n e r a l l y a c q u i r e d b y l o n g - t e r m b u r i a l , b y c h e m i c a l extraction
Beck; Archaeological Chemistry Advances in Chemistry; American Chemical Society: Washington, DC, 1974.
244
ARCHAEOLOGICAL
CHEMISTRY
of t h e c o l l a g e n o f m o d e r n i v o r y . O u r e x p e r i e n c e suggests that s u c h treat m e n t effecting
o n l y l i m i t e d r e m o v a l of t h e c o l l a g e n
is u s u a l l y a c c o m
p a n i e d b y severe loss o f m e c h a n i c a l strength. T h e d a t a f o r t h e A s s y r i a n i v o r y c i t e d i n T a b l e V I I I are n o t consistent w i t h those f o r a n y o f t h e excavated
specimens.
Related Problems. an
T h e first q u e s t i o n to b e resolved i n e x a m i n i n g
A n c i e n t N e a r E a s t e r n i v o r y object o f u n k n o w n p r o v e n a n c e is its
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a n t i q u i t y . P e r h a p s e q u a l l y significant is t h e q u e s t i o n o f assignment to a specific a r c h a e o l o g i c a l site. T h i s p r o b l e m , as y e t u n e x p l o r e d , m a y u l t i m a t e l y d e p e n d o n t h e s t u d y o f trace element d i s t r i b u t i o n s f o r its t e c h n i c a l resolution. A t this t i m e t h e most p o w e r f u l t e c h n i q u e a v a i l a b l e t o s t u d y these problems
is t h e a r t h i s t o r i a n s stylistic analysis.
T h e cooperation
of
archeologists a n d art historians w i l l b e a p r e r e q u i s i t e f o r progress i n t h e t e c h n i c a l analysis o f ivories. Acknowledgment W e thank V a u g h n E . C r a w f o r d , Oscar W h i t e Muscarella, a n d P r u d e n c e O l i v e r H a r p e r o f t h e M e t r o p o l i t a n M u s e u m of A r t f o r samples o f ancient
ivory, permission
to sample
the Khorsabad
ivories, a n d f o r
s t i m u l a t i n g discussions.
Literature Cited 1. Barnett, R., "A Catalogue of the Nimrud Ivories, with other Examples of Ancient Near Eastern Ivories in the British Museum," British Museum, London, 1957. 2. Wilkinson, C. K., "The First Millennium B. C.," Metrop. Museum Art Bull. (1960) 18, 261-268. 3. Mallowan, M. E. L., "Nimrud and its Remains," Dodd, Mead, New York, 1966. 4. Muscarella, O. W., "Hasanlu 1964," Metrop. Museum Art Bull. (1966) 25, 121-135. 5. Mallowan, M., Davies, L. G., "Ivories in the Assyrian Style," The British School of Archaeology in Iraq, London, 1970. 6. Baer, N. S., Indictor, N., Frantz, J. H., Appelbaum, B., "The Effect of High Temperature on Ivory," Studies in Conservation (1971) 16, 1-8. 7. Baer, N. S., Appelbaum, B., Indictor, N., "The Effect of Long-Term Heat ing on Ivory," Int. Inst. Conserv., Amer. Group Bull. (1971) 12, 55-59. 8. Langer, W. L., Ed., "An Encyclopedia of World History," rev. 3rd ed., pp. 25-38, Houghton-Mifflin, Boston, 1952. 9. Groff, D. W., "Gas Chromatography Methods for Bone Fluorine and Nitro gen Components," in "Science and Archaeology," Chap. 20, MIT Press, Boston, 1971. 10. Baer, N. S., Majewski, L. J., "Ivory and Related Materials: An Annotated Bibliography, Section A: Conservation and Scientific Examination," Art Archaeol. Tech. Abstr. (1970) 8, 229-275. 11. Weiner, J. S., Oakley, K. P., Le Gros Clark, W. E., "The Solution of the Piltdown Problem," Geology (1953) 2, 139-146.
Beck; Archaeological Chemistry Advances in Chemistry; American Chemical Society: Washington, DC, 1974.
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13.
BAER
A N D INDICTOR
IvOTU
Artifacts
245
12. Oakley, K. P., Weiner, J. S., "Piltdown Man," Amer. Scientist (1955) 43, 573-583. 13. Middleton, J., "On Fluorine in Bones, its Source, and its Application to the Determination of the Geological Age of Fossil Bones," Proc. Geol. Soc. London (1844) 4, Pt. 2 (99), 431-433. 14. Carnot, Α., "Researches on Fluorine in Modern Bone and in Fossil Bone," Compt. Rend. Acad. Sci. (1892) 114, 1189-1192. 15. De Vries, H., Oakley, K. P., "Radiocarbon Dating of the Piltdown Skull and Jaw," Nature (1959) 184, 224-226. 16. Ho, T. Y., Marcus, L. F., Berger, R., "Radiocarbon Dating of Petroleum -Impregnated Bone from Tar Pits at Rancho La Brea, California," Science (1969) 164, 1051-1052. 17. Morrison, R. T., Boyd, R. N., "Organic Chemistry," pp. 242-243, Allyn and Bacon, Boston, 1959. 18. Schwarzkopf, Otto, private communication. 19. Jaffe, Ε. B., Sherwood, A. M., "Physical and Chemical Comparison of Mod ern and Fossil Tooth and Bone Material," U.S. Geol. Surv. (1951) T.E.M.-149. 20. Plenderleith, H. J., Werner, Α. Ε. Α., "The Conservation of Antiquities and Works of Art," 2nd ed., Chap. 6, Oxford University Press, London, 1971. 21. Crawford, Vaughn E., private communication. 22. Baer, N. S., Indictor, N., unpublished data. RECEIVED August 20,
1973.
Beck; Archaeological Chemistry Advances in Chemistry; American Chemical Society: Washington, DC, 1974.
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ARCHAEOLOGICAL CHEMISTRY
Beck; Archaeological Chemistry Advances in Chemistry; American Chemical Society: Washington, DC, 1974.
