- Email: [email protected]
Non-destructive analysis and identification of jade by PIXE
Nuclear Instruments and Methods in Physics Research B 219–220 (2004) 30–34 www.elsevier.com/locate/nimb
Non-destructive analysis and identification of jade by PIXE H.S. Cheng *, Z.Q. Zhang, B. Zhang, F.J. Yang Institute of Modern Physics, Fudan University, Shanghai 200433, PR China
Abstract This paper reports the experimental results of identifying jade by proton induced X-ray emission (PIXE) technique. It is found that the jade can be classified, according to the chemical composition determined by PIXE. The experimental results can differentiate ancient Chinese jade works of art from fakes if the material is the same. Ó 2004 Elsevier B.V. All rights reserved. PACS: 32.30.Rj; 82.80.Ej; 91.65.Nd Keywords: PIXE; Identification; Antique jade
1. Introduction Jade has a long history among the ancient people of China and Central America. Jade consists of two principle minerals: nephrite and jadeite. Nephrite is a calcium magnesium silicate, widely found. The rare variety of jade is jadeite, a pyroxene mineral of sodium aluminum silicate. In China, the early jadeite was found late in the W-Han Dynasty (BC 206–AD 25). The nephrite artifacts were found as early as the Hong-Shan culture period (about BC 3000) in the tombs. Among the inhabitants of China, jadeite and nephrite are highly valued. Other stones such as serpentine, Du-Shan jade, Jingbai jade, even quartz were also artistically valued. All pure jadeite, nephrite, serpentine, Jingbai jade and calcite are white in color. Their outside features are
similar making it difficult to differentiate with the naked eyes. PIXE is used to measure the chemical composition non-destructively and classifies the chemical composition of jade. The experimental results also differentiate ancient Chinese jade from fakes. The differences can be detected by surface changes in the material composition, due to interaction with the environment of the ancient artifacts. Since the ‘‘chicken bone white’’ patina of ancient artifacts can be simulated for contemporary articles by soaking in HCl and H2 SO4 , leaving a telltale contamination of Cl and S not found in authentic specimens. This means that PIXE can be used for the discrimination of genuine from fake relics fabricated of jade.
2. Experiment 2.1. Samples
*
Corresponding author. Tel.: +86-21-6564-3460; fax: +8621-6564-2787. E-mail address: [email protected] (H.S. Cheng).
The samples studied were from the gem and jade factories of Shanghai and Shanghai Museum.
0168-583X/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.nimb.2004.01.023
H.S. Cheng et al. / Nucl. Instr. and Meth. in Phys. Res. B 219–220 (2004) 30–34
The ancient jade used was unearthed from YaoShan relic, Zhejiang province. 2.2. Experiment Experiments were performed at the Institute of Modern Physics, Fudan University, Shanghai. An external-beam PIXE was applied, using a beamline of the 9SDH-2 3.0 MeV tandem accelerator on samples placed at 10 mm outside the beam exit window (7.5 lm Kapton). After passing through the Kapton film and air, 2.8 MeV protons with beam current of 0.05–0.5 nA hit the sample with a small spot 1 mm in diameter. The induced X-rays were detected, using an ORTEC Si(Li) detector with an energy resolution of 165 eV (FWHM) at 5.9 keV. From the measured PIXE spectrum, the chemical composition (Z P 12) in the sample was obtained using the de-convolution program GUPIXE-96 [1]. Information of Na was lost because of the X-ray absorption by air.
3. Experimental results 3.1. The classification of jade by measured chemical composition Fig. 1 shows a typical PIXE spectrum measured from a nephrite carving. Strong X-ray
Fig. 1. A PIXE spectrum measured from a nephrite carving.
31
peaks of Mg, Si and Ca are present, and the elements K, Mn and Fe also can be seen, which are present as the chemical impurity in the sample. The chemical compositions of various jade measured by PIXE are indicated with capital initials in Table 1, together with the calculated data noted by EXP and CAL, respectively. The calculated values are obtained from the pure mineral chemical formula, which is also listed in Table 1. The measured major chemical compositions are very close to the calculated values. It means the jade is quite pure chemically [2–4]. The pure nephrite is white in color, tending to be darker with additional Fe2þ as shown in Table 1. From the measured chemical composition, the sample is easy to be classified. Table 1 also lists the chemical composition of a jade carving with white color. According to the chemical composition, this carving is made from the Jingbai jade or agate, a silicon dioxide stone. In many cases, the jade carving could be easily classified from the measured PIXE spectrum without calculation. 3.2. The differentiation of Chinese ancient jade In China, most of jade collectors like to have the ancient jade unearthed from the Neolithic relics, the Liang-Zhu culture relics (BC 2000), Hong-Shan culture relics (BC 3000). Of course, there are not a lot of such relics in existence. Recently, many fake ancient jade products appeared on the market. For the ancient jade earthed for thousands years, the chemical composition of the surface region will change as a result of the interaction between jade and the water and soil. This natural process also makes the samples appear a special white color or in Chinese terms, a ‘‘chicken bone white’’. Table 2 lists the chemical composition of the ancient jade surface region measured by PIXE. From Table 2, we can see that the MgO measured from the unearthed Yao-Shan jade from the Liang-Zhu culture period (BC 2000), is between 17.41 and 21.88 wt.%. This weight is much lower than the standard mineral content of 24.69 wt.%. Also, for the jade cup unearthed from W-Han
32
Sample Nephrite
EXP
MgO
Al2 O3
White Green Blue
23.01 ± 1.50 23.27 ± 1.50 22.08 ± 1.44 24.69
2.00 ± 0.13 1.94 ± 0.13 1.86 ± 0.12 –
CAL
SiO2
K2 O
CaO
MnO
Fe2 O3
Chemical composition
59.04 ± 3.84 56.74 ± 3.69 56.98 ± 3.70 59.26
0.050 ± 0.005 0.038 ± 0.004 0.031 ± 0.003 –
13.40 ± 0.87 12 99 ± 0.84 12.43 ± 0.81 13.83
0.071 0.084 0 –
0.360 ± 0.023 0.941 ± 0.061 3.989 ± 0.259 –
Ca2 (Mg,Fe2þ )5 [Si4 O11 ]2 (OH)2
Serpentine
EXP CAL
White
40.90 ± 2.62 43.48
– –
44.46 ± 2.89 43.48
– –
0.582 ± 0.038 –
– –
1.09 ± 0.071 –
Mg3 [Si2 O5 ](OH)4
Jadeite
EXP CAL
White
– –
25.31 ± 1.65 25.25
59.36 ± 3.86 59.41
– –
0.72 ± 0.07 –
– –
0.290 ± 0.019 –
NaAl[Si2 O6 ]
Dushan jade
EXP CAL
White
0.70 ± 0.05 –
35.51 ± 2.31 36.69
44.76 ± 2.91 43.17
2.52 ± 0.16 –
15.58 ± 1.01 20.14
– –
0.735 ± 0.048 –
Ca[Al2 Si2 O8 ]
Jingbai jade
EXP
White
6.66 ± 0.43
9.86 ± 0.64
81.70 ± 5.30
0.033 ± 0.003
0.218 ± 0.022
–
0.012 ± 0.001
SiO2
Quartz
EXP
Purple
–
1.10 ± 0.1
98.46 ± 3.94
0.09 ± 0.01
0.511 ± 0.05
–
0.012 ± 0.001
Agate
EXP CAL
Blue
2.82 ± 0.18
4.48 ± 0.29
86.17 ± 3.45 100
2.976 ± 0.19
0.905 ± 0.059
–
2.655 ± 0.173
A jade carving
EXP
White
5.24 ± 0.34
9.22 ± 0.60
83.96 ± 3.36
0.030 ± 0.003
0.022 ± 0.002
–
0.029 ± 0.003
H.S. Cheng et al. / Nucl. Instr. and Meth. in Phys. Res. B 219–220 (2004) 30–34
Table 1 The chemical compositions of various jade samples measured by PIXE (wt.%)
MgO
Al2 O3
SiO2
S
Cl
K2 O
CaO
MnO
Fe2 O3
Yao-Shan Jade (Nephrite)
Samples Jade arrow M2 M3-9 M3-20 M6-8
20.53 ± 1.33 21.24 ± 1.38 17.41 ± 1.13 21.88 ± 1.42 20.89 ± 1.36
1.86 ± 0.12 4.53 ± 0.29 5.18 ± 0.34 3.42 ± 0.22 3.82 ± 0.25
59.82 ± 3.89 58.09 ± 3.78 61.64 ± 4.00 57.90 ± 3.76 59.96 ± 3.90
0.26 ± 0.03 0.27 ± 0.03 0.21 ± 0.02 0.304 ± 0.030 0.26 ± 0.03
0.025 ± 0.003 0.026 ± 0.003 0.036 ± 0.004 0.012 ± 0.001 0.025 ± 0.003
0.12 ± 0.01 0.19 ± 0.02 0.34 ± 0.03 0.13 ± 0.01 0.16 ± 0.02
12.91 ± 0.84 11.92 ± 0.77 10.43 ± 0.68 12.34 ± 0.80 12.36 ± 0.80
0.040 ± 0.004 0.060 ± 0.006 0.070 ± 0.007 0.070 ± 0.007 0.050 ± 0.005
1.51 ± 0.098 0.96 ± 0.06 1.15 ± 0.07 0.99 ± 0.06 0.81 ± 0.05
Jade Cup (Nephrite)
Normal position Chicken bone white part
25.74 ± 1.67
2.71 ± 0.18
56.89 ± 3.70
0.153 ± 0.015 0.010 ± 0.001 0.13 ± 0.01
11.72 ± 0.76
0.016 ± 0.002 0.175 ± 0.011
15.90 ± 1.03
6.23 ± 0.40
55.22 ± 3.59
0.286 ± 0.029 0.010 ± 0.001 0.299 ± 0.03
19.26 ± 1.25
–
19.57 ± 1.27
–
58.23 ± 3.78
0.257 ± 0.026 0.36 ± 0.04
0.29 ± 0.03
12.80 ± 0.83
0.051 ± 0.005 5.21 ± 0.34
0.86 ± 0.06
33.66 ± 2.19
5.17 ± 0.36
0.179 ± 0.018 0.37 ± 0.04
51.00 ± 3.32
0.042 ± 0.04
–
60.82 ± 3.95
0.21 ± 0.02
0.10 ± 0.01
13.5 ± 0.90
0.037 ± 0.004 0.35 ± 0.02
Imitative jade handle of sword (Nephrite) Imitative jade Cong Jade soaked by hydrochloric acid (Nephrite)
7.32 ± 0.48 21.61 ± 1.40
0.15 ± 0.02
0.191 ± 0.012
1.35 ± 0.09
H.S. Cheng et al. / Nucl. Instr. and Meth. in Phys. Res. B 219–220 (2004) 30–34
Table 2 The chemical composition of ancient jade measured from the surface region by PIXE
33
34
H.S. Cheng et al. / Nucl. Instr. and Meth. in Phys. Res. B 219–220 (2004) 30–34
Dynasty tomb (BC 206-AD 25), the contents of MgO measured from the ‘‘chicken bone white’’ part is much lower than normal. The detail of the chemical reaction process has not been well understood. The imitative ancient jade artifacts, which were soaked in acid (the mixture of hydrochloric acid, sulfuric acid and nitric acid), appeared similar to ‘‘chicken bone white’’ color. The MgO is also lower than the standard, as shown in Table 2. Experimental results show the Cl in the imitation samples is higher than in the originals: they are P 0.1 wt.% and 6 0.036 wt.%, respectively, as listed in Table 2. The S in the imitation samples is sometimes also larger than that of originals, sometimes as large as 3–5 wt.%. The higher S is probably the result of the sample being soaked in sulfuric acid to make the ‘‘chicken bone white’’ color.
4. Summary PIXE can be used to measure the chemical composition of jade non-destructively. The jade can be classified, using the chemical composition measured by PIXE. The ancient Chinese jade can also be distinguished from the fakes according to the Cl or S contents measured from sample by PIXE. References [1] J.L. Campbell, J.A. Maxwell, Gupix 96: The Guelph PIXE Program, Univerity of Guelph, Ontario, Canada, 1996. [2] H.S. Cheng, G. Chen, H.X. Zhu, F.J. Yang, Nucl. Tech. 22 (4) (1999) 233. [3] H.X. Zhu, H.S. Cheng, F.J. Yang, Nucl. Tech. 24 (2) (2001) 149. [4] E.K. Lin, C.W. Wang, Y.C. Yu, T.Y. Liu, H.S. Cheng et al., Int. J. PIXE 9 (1999) 423.
Non-destructive analysis and identification of jade by PIXE H.S. Cheng *, Z.Q. Zhang, B. Zhang, F.J. Yang Institute of Modern Physics, Fudan University, Shanghai 200433, PR China
Abstract This paper reports the experimental results of identifying jade by proton induced X-ray emission (PIXE) technique. It is found that the jade can be classified, according to the chemical composition determined by PIXE. The experimental results can differentiate ancient Chinese jade works of art from fakes if the material is the same. Ó 2004 Elsevier B.V. All rights reserved. PACS: 32.30.Rj; 82.80.Ej; 91.65.Nd Keywords: PIXE; Identification; Antique jade
1. Introduction Jade has a long history among the ancient people of China and Central America. Jade consists of two principle minerals: nephrite and jadeite. Nephrite is a calcium magnesium silicate, widely found. The rare variety of jade is jadeite, a pyroxene mineral of sodium aluminum silicate. In China, the early jadeite was found late in the W-Han Dynasty (BC 206–AD 25). The nephrite artifacts were found as early as the Hong-Shan culture period (about BC 3000) in the tombs. Among the inhabitants of China, jadeite and nephrite are highly valued. Other stones such as serpentine, Du-Shan jade, Jingbai jade, even quartz were also artistically valued. All pure jadeite, nephrite, serpentine, Jingbai jade and calcite are white in color. Their outside features are
similar making it difficult to differentiate with the naked eyes. PIXE is used to measure the chemical composition non-destructively and classifies the chemical composition of jade. The experimental results also differentiate ancient Chinese jade from fakes. The differences can be detected by surface changes in the material composition, due to interaction with the environment of the ancient artifacts. Since the ‘‘chicken bone white’’ patina of ancient artifacts can be simulated for contemporary articles by soaking in HCl and H2 SO4 , leaving a telltale contamination of Cl and S not found in authentic specimens. This means that PIXE can be used for the discrimination of genuine from fake relics fabricated of jade.
2. Experiment 2.1. Samples
*
Corresponding author. Tel.: +86-21-6564-3460; fax: +8621-6564-2787. E-mail address: [email protected] (H.S. Cheng).
The samples studied were from the gem and jade factories of Shanghai and Shanghai Museum.
0168-583X/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.nimb.2004.01.023
H.S. Cheng et al. / Nucl. Instr. and Meth. in Phys. Res. B 219–220 (2004) 30–34
The ancient jade used was unearthed from YaoShan relic, Zhejiang province. 2.2. Experiment Experiments were performed at the Institute of Modern Physics, Fudan University, Shanghai. An external-beam PIXE was applied, using a beamline of the 9SDH-2 3.0 MeV tandem accelerator on samples placed at 10 mm outside the beam exit window (7.5 lm Kapton). After passing through the Kapton film and air, 2.8 MeV protons with beam current of 0.05–0.5 nA hit the sample with a small spot 1 mm in diameter. The induced X-rays were detected, using an ORTEC Si(Li) detector with an energy resolution of 165 eV (FWHM) at 5.9 keV. From the measured PIXE spectrum, the chemical composition (Z P 12) in the sample was obtained using the de-convolution program GUPIXE-96 [1]. Information of Na was lost because of the X-ray absorption by air.
3. Experimental results 3.1. The classification of jade by measured chemical composition Fig. 1 shows a typical PIXE spectrum measured from a nephrite carving. Strong X-ray
Fig. 1. A PIXE spectrum measured from a nephrite carving.
31
peaks of Mg, Si and Ca are present, and the elements K, Mn and Fe also can be seen, which are present as the chemical impurity in the sample. The chemical compositions of various jade measured by PIXE are indicated with capital initials in Table 1, together with the calculated data noted by EXP and CAL, respectively. The calculated values are obtained from the pure mineral chemical formula, which is also listed in Table 1. The measured major chemical compositions are very close to the calculated values. It means the jade is quite pure chemically [2–4]. The pure nephrite is white in color, tending to be darker with additional Fe2þ as shown in Table 1. From the measured chemical composition, the sample is easy to be classified. Table 1 also lists the chemical composition of a jade carving with white color. According to the chemical composition, this carving is made from the Jingbai jade or agate, a silicon dioxide stone. In many cases, the jade carving could be easily classified from the measured PIXE spectrum without calculation. 3.2. The differentiation of Chinese ancient jade In China, most of jade collectors like to have the ancient jade unearthed from the Neolithic relics, the Liang-Zhu culture relics (BC 2000), Hong-Shan culture relics (BC 3000). Of course, there are not a lot of such relics in existence. Recently, many fake ancient jade products appeared on the market. For the ancient jade earthed for thousands years, the chemical composition of the surface region will change as a result of the interaction between jade and the water and soil. This natural process also makes the samples appear a special white color or in Chinese terms, a ‘‘chicken bone white’’. Table 2 lists the chemical composition of the ancient jade surface region measured by PIXE. From Table 2, we can see that the MgO measured from the unearthed Yao-Shan jade from the Liang-Zhu culture period (BC 2000), is between 17.41 and 21.88 wt.%. This weight is much lower than the standard mineral content of 24.69 wt.%. Also, for the jade cup unearthed from W-Han
32
Sample Nephrite
EXP
MgO
Al2 O3
White Green Blue
23.01 ± 1.50 23.27 ± 1.50 22.08 ± 1.44 24.69
2.00 ± 0.13 1.94 ± 0.13 1.86 ± 0.12 –
CAL
SiO2
K2 O
CaO
MnO
Fe2 O3
Chemical composition
59.04 ± 3.84 56.74 ± 3.69 56.98 ± 3.70 59.26
0.050 ± 0.005 0.038 ± 0.004 0.031 ± 0.003 –
13.40 ± 0.87 12 99 ± 0.84 12.43 ± 0.81 13.83
0.071 0.084 0 –
0.360 ± 0.023 0.941 ± 0.061 3.989 ± 0.259 –
Ca2 (Mg,Fe2þ )5 [Si4 O11 ]2 (OH)2
Serpentine
EXP CAL
White
40.90 ± 2.62 43.48
– –
44.46 ± 2.89 43.48
– –
0.582 ± 0.038 –
– –
1.09 ± 0.071 –
Mg3 [Si2 O5 ](OH)4
Jadeite
EXP CAL
White
– –
25.31 ± 1.65 25.25
59.36 ± 3.86 59.41
– –
0.72 ± 0.07 –
– –
0.290 ± 0.019 –
NaAl[Si2 O6 ]
Dushan jade
EXP CAL
White
0.70 ± 0.05 –
35.51 ± 2.31 36.69
44.76 ± 2.91 43.17
2.52 ± 0.16 –
15.58 ± 1.01 20.14
– –
0.735 ± 0.048 –
Ca[Al2 Si2 O8 ]
Jingbai jade
EXP
White
6.66 ± 0.43
9.86 ± 0.64
81.70 ± 5.30
0.033 ± 0.003
0.218 ± 0.022
–
0.012 ± 0.001
SiO2
Quartz
EXP
Purple
–
1.10 ± 0.1
98.46 ± 3.94
0.09 ± 0.01
0.511 ± 0.05
–
0.012 ± 0.001
Agate
EXP CAL
Blue
2.82 ± 0.18
4.48 ± 0.29
86.17 ± 3.45 100
2.976 ± 0.19
0.905 ± 0.059
–
2.655 ± 0.173
A jade carving
EXP
White
5.24 ± 0.34
9.22 ± 0.60
83.96 ± 3.36
0.030 ± 0.003
0.022 ± 0.002
–
0.029 ± 0.003
H.S. Cheng et al. / Nucl. Instr. and Meth. in Phys. Res. B 219–220 (2004) 30–34
Table 1 The chemical compositions of various jade samples measured by PIXE (wt.%)
MgO
Al2 O3
SiO2
S
Cl
K2 O
CaO
MnO
Fe2 O3
Yao-Shan Jade (Nephrite)
Samples Jade arrow M2 M3-9 M3-20 M6-8
20.53 ± 1.33 21.24 ± 1.38 17.41 ± 1.13 21.88 ± 1.42 20.89 ± 1.36
1.86 ± 0.12 4.53 ± 0.29 5.18 ± 0.34 3.42 ± 0.22 3.82 ± 0.25
59.82 ± 3.89 58.09 ± 3.78 61.64 ± 4.00 57.90 ± 3.76 59.96 ± 3.90
0.26 ± 0.03 0.27 ± 0.03 0.21 ± 0.02 0.304 ± 0.030 0.26 ± 0.03
0.025 ± 0.003 0.026 ± 0.003 0.036 ± 0.004 0.012 ± 0.001 0.025 ± 0.003
0.12 ± 0.01 0.19 ± 0.02 0.34 ± 0.03 0.13 ± 0.01 0.16 ± 0.02
12.91 ± 0.84 11.92 ± 0.77 10.43 ± 0.68 12.34 ± 0.80 12.36 ± 0.80
0.040 ± 0.004 0.060 ± 0.006 0.070 ± 0.007 0.070 ± 0.007 0.050 ± 0.005
1.51 ± 0.098 0.96 ± 0.06 1.15 ± 0.07 0.99 ± 0.06 0.81 ± 0.05
Jade Cup (Nephrite)
Normal position Chicken bone white part
25.74 ± 1.67
2.71 ± 0.18
56.89 ± 3.70
0.153 ± 0.015 0.010 ± 0.001 0.13 ± 0.01
11.72 ± 0.76
0.016 ± 0.002 0.175 ± 0.011
15.90 ± 1.03
6.23 ± 0.40
55.22 ± 3.59
0.286 ± 0.029 0.010 ± 0.001 0.299 ± 0.03
19.26 ± 1.25
–
19.57 ± 1.27
–
58.23 ± 3.78
0.257 ± 0.026 0.36 ± 0.04
0.29 ± 0.03
12.80 ± 0.83
0.051 ± 0.005 5.21 ± 0.34
0.86 ± 0.06
33.66 ± 2.19
5.17 ± 0.36
0.179 ± 0.018 0.37 ± 0.04
51.00 ± 3.32
0.042 ± 0.04
–
60.82 ± 3.95
0.21 ± 0.02
0.10 ± 0.01
13.5 ± 0.90
0.037 ± 0.004 0.35 ± 0.02
Imitative jade handle of sword (Nephrite) Imitative jade Cong Jade soaked by hydrochloric acid (Nephrite)
7.32 ± 0.48 21.61 ± 1.40
0.15 ± 0.02
0.191 ± 0.012
1.35 ± 0.09
H.S. Cheng et al. / Nucl. Instr. and Meth. in Phys. Res. B 219–220 (2004) 30–34
Table 2 The chemical composition of ancient jade measured from the surface region by PIXE
33
34
H.S. Cheng et al. / Nucl. Instr. and Meth. in Phys. Res. B 219–220 (2004) 30–34
Dynasty tomb (BC 206-AD 25), the contents of MgO measured from the ‘‘chicken bone white’’ part is much lower than normal. The detail of the chemical reaction process has not been well understood. The imitative ancient jade artifacts, which were soaked in acid (the mixture of hydrochloric acid, sulfuric acid and nitric acid), appeared similar to ‘‘chicken bone white’’ color. The MgO is also lower than the standard, as shown in Table 2. Experimental results show the Cl in the imitation samples is higher than in the originals: they are P 0.1 wt.% and 6 0.036 wt.%, respectively, as listed in Table 2. The S in the imitation samples is sometimes also larger than that of originals, sometimes as large as 3–5 wt.%. The higher S is probably the result of the sample being soaked in sulfuric acid to make the ‘‘chicken bone white’’ color.
4. Summary PIXE can be used to measure the chemical composition of jade non-destructively. The jade can be classified, using the chemical composition measured by PIXE. The ancient Chinese jade can also be distinguished from the fakes according to the Cl or S contents measured from sample by PIXE. References [1] J.L. Campbell, J.A. Maxwell, Gupix 96: The Guelph PIXE Program, Univerity of Guelph, Ontario, Canada, 1996. [2] H.S. Cheng, G. Chen, H.X. Zhu, F.J. Yang, Nucl. Tech. 22 (4) (1999) 233. [3] H.X. Zhu, H.S. Cheng, F.J. Yang, Nucl. Tech. 24 (2) (2001) 149. [4] E.K. Lin, C.W. Wang, Y.C. Yu, T.Y. Liu, H.S. Cheng et al., Int. J. PIXE 9 (1999) 423.