American International Journal of Available online at http://www.iasir.net Research in Formal, Applied & Natural Sciences ISSN (Print): 2328-3777, ISSN (Online): 2328-3785, ISSN (CD-ROM): 2328-3793 AIJRFANS is a refereed, indexed, peer-reviewed, multidisciplinary and open access journal published by International Association of Scientific Innovation and Research (IASIR), USA (An Association Unifying the Sciences, Engineering, and Applied Research)

Analytical and Characterisation Study of Heavily Oxidized Billon , Tell Basta, Egypt Dr. Saleh Mohamed Saleh, Dr. Mohamed M. Megahed Faculty of Archaeology, Fayoum University, Egypt Abstract: Some have been excavated since 1998 by the Supreme Council of Antiquities Mission in Tell Basta, El- Sharqyia governorate, Egypt. The coins were found in a salty soil suffering from large quantity of corrosion products, which were mixed with soil deposits. This work aims to evaluate and identify the influence of compositions and corrosion processes in the burial environment on the corrosion rate. Stereomicroscope, scanning electron microscope (SEM) with energy dispersive spectrometry (EDS) and X- ray diffraction (XRD) were used to characterize coinage technology, surface morphology, corrosion products, and chloride ion diffusion rate. The results signify that billon coins contain in metallic case in the core with a small quantity of silver corrosion products on the surface. In contrast, was less in the core, and the majority of it has totally turned the core into corrosion products. Keywords: Archaeological Billon Coins, Copper, Silver, Coinage Technology, Burial Environment Corrosion Products, Stereo Microscope, X-Ray Diffraction, Scanning Electron Microscope/ Energy Dispersive Spectrometry.

I. Introduction Coins form a unique class of archaeological material (Seeley, 1980), and they are a prevalent cultural material than other artifacts because coins have survival rate (Alsaa’d, 1999). Also, coins are made of different to supply denomination to cover the range of transactions (Butcher and Ponting, 2014). They are often made at the royal mint, and they have a technical attribute of its era. Silver is usually alloyed with copper, and even if there is 50/50 Cu/Ag, the appearance of this alloy is still white (Grassini, Angelini, Palumbo and Ingo, 2008). Billon alloy is consisting of or silver and a base metal, usually copper, used especially for coinage (Scheidel, 2010, Kelly, 2005) or it is an alloy of copper and silver, with more than half copper. Large quantities of billon coins were produced in the Roman era (Clayton, 2013). The use of copper instead of gold or silver may have raised the level of tolerance of coin overvaluation relative to metal value, the underlying principle was the same as with precious-metal coins: the market value of coin was primarily a function of its intrinsic value and crude attempts to introduce token coins were invariably unsuccessful. Billon alloy is a low-grade metal after gold alloys (Hrenderson, 1953). Bimetallic system using silver and copper has been little studied to date. Silver was one of the first to be used by humans, and it is found in many archaeological objects such as coins, jewellery and ornaments (Selwyn, 2004). Silver has been known longer than recorded history (around 3000 B.C). The Romans are the first to mention the use of silver (www.footdefense.com). Copper is the most important non-ferrous metal that was used in early times (Renfrew and Bahn, 2004), and copper ore occurs within the geographical limits of Egypt in two different localities, namely in Sinai and the eastern desert (Lucas, 1927). II. Corrosion process of Billon Coin Corrosion process of billon alloy is complicated. The in-situ corrosion caused by interaction between metals and surrounding soil changed in the coin’s morphology. The burial corrosive environment is sandy soil rich with high salts and chloride ions. The site is characterized by rising of lime and gypsum. Selwyn and other said that a complete understanding of the corrosion of metal artifacts requires consideration of both the changes that occur while the object is buried and how these changes affect corrosion after excavation (Selwyn, Sirois and Argyropoulos, 1999). Soil or subterranean corrosion occurs within an electrolytic film, created by the moisture constantly present within the inter-granular spaces and organic matter of soil or sediment. The variation of chemical and physical properties of soil and soil water alter the properties of the electrolyte in terms of pH, pollutants and oxidizing properties (Dracott, 2014). The amount of precipitation is the main effect of climate and alloying elements, which results in electrons loss (Domoneand, and Jefferis, 2002, Ferreira, Ponciana, Vaitsinan, and Pérez, 2007). Metallic corrosion in general produces metal ions oxidized in the hydrated form and then precipitates a mass of corrosion compounds in the solid form (Sato, 2012). Electrolytic corrosion is a result of direct current from outside sources entering and then leaving a particular metallic structure by way of the electrolyte (Bushman, 2010). Also, electrochemical corrosion occurs when counterbalancing reduction reaction at cathodic sites that consumes the generated electrons (Selwyn, Sirois and Argyropoulos, 1999). The

AIJRFANS 15-506; © 2015, AIJRFANS All Rights Reserved Page 1 Saleh and Megahed, American International Journal of Research in Formal, Applied & Natural Sciences, 13(1), December, 2015- February, 2016, pp. 01-09 copper-silver played a serious role in corrosion process, because of the difference between the two metals in the potential, and surely the copper was the victim. The presence of copper causes the brittle of billon coins (Thompson and Chatterjee, 1954). Corrosion and internal leaching and dissolving of copper can result in a considerable loss of weight over time (Butcher and Ponting, 2014). Erosion corrosion is indicated by an increased rate of deterioration and degradation on a metal, because of the relative movement between a corrosive fluid and a metal surface (Macleod and Schindelholz, 2004). Chloride corrosion compounds form under these conditions will tend to precipitate rapidly and be powdery rather than crystalline in texture (Sharkey and Lewin, 1971). At the same time, chloride ions are not combined in a stable solid corrosion product. They take part in the metal corrosion cycle, and once the artifact becomes completely mineralized, they diffuse into the burial soil (Turgoose, 1982). Hydrated copper (II) salts are generally blue or green in colour, both as solids and in aqueous solution. In concentrated hydrochloric acid, however, they become yellow or red-violet, respectively, to the formation of complex anions. Anhydrous copper (II) salts are usually black or yellow-brown from the sulphate which is white. Copper (II) sulphate, chloride and acetate are very soluble in water (Burns, Townshend and Carter, 1981). Patina has indicated a desirable and attractive surface condition indicative of age (Weil, 2007). III. Description and Condition Archaeological billon coins were discovered by The Supreme Council of Antiquities Mission in Tell Basta, El- Sharqia governorate, Egypt, season 1998. Figure 1: Sceenshot fom Google earth of Tell Basta

After: https://earth.google.com Excavated antiquities and coins are dated back to the Roman period according to the archaeological documentation from the decoration as shown in figure 2. After the excavation, coins were preserved in uncontrolled environment, so post-corrosion resulted from chlorides led to transformation into corrosion. Billon coins were in close by corrosion products and soil deposits. The most of coin decorative were removed gradually during burial. In generally, corrosion products changed in the morphology of billon coins. Archaeological coins removed from the soil are likely to have coloured cover were dependent on soil properties. The predominantly coins had lost mint , and fragments were not restored, because they were highly mineralized. Photo 1: (A) Front of the billon coin, (b) Back of the billon coin after treatment

A B

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IV. Materials and Methods A. Sample collection Coin fragments were examined and analyzed by stereo microscope and SEM-EDS without embedding and mounting. Random Powder samples were used in XRD analyses. Fragment surfaces were not cleaned prior examination and analyses. Investigation and analysis were organized into one fragment from the excavated coins. B. Stereo microscope A deep examination and photography for the coin fragments were performed by using stereo microscope in order to declare the structure of the coin surface, and the stratified corrosion layers. It is the oldest and simplest investigation method. The investigation was implemented using Zeiss microscope. C. Scanning Electron Microscope and Energy Dispersive Spectrometry (SEM/EDS):- Scanning electron microscopy is a valuable tool for the examination and analyses of archaeological coins, because of the possibility of high magnification, high depth resolution, and chemical analysis. Examination of samples in high magnifications allows for identification of the metal artifacts microstructure and their oxidized form. Scanning electron microscopy based on the detection and treatment of X-rays emitted after excitation of the sample ray energy is characteristic from which emitted intensity characteristic of the concentration of the sample (www.engr.sjsu.edu/MC2/SOP_EDAX.pdf). Magnification in the SEM is controlled by the ratio of the dimensions of the Cathode Ray Tube (CRT) to the dimensions of the area being scanned (Dunlap and Adaskaveg, 1997). SEM-EDS was used in investigation and measurement of the elements in the coin alloy, corrosion compounds and soil deposits. D. X-Ray diffraction Analysis X-ray powder diffractometry involves characterization of materials by using data dependent on the atomic arrangement in the crystal lattice. The technique uses single or multiphase specimens. Each 2Θ value is converted to a d-spacing, using Bragg’s law to generate a list of d-spacing and intensity called a d/I list (Winefordner, 2012). X-RD analysis was performed by a Phillips PW 1840 series powder diffractometer, using CuK radiation. Measurements were carried out in the range 3˚ < 2Θ < 65◦ with a step of 0.01◦.

V. Results A. Microscopic investigation Photo 2: Stereo microscope photos of billon fragments indicate (a) Observe surface of the billon coin, (b) Reverse surface of the billon coin, (c) Cross section of the billon coin, (d) The coin edge.

(a) (b) (c) (d) The previous photos clarified that corrosion products were mixed with soil encrustations covering the coin surfaces. Fragments have a thick layer of corrosion combined to soil deposits. As shown in photo (1a), the nodule formations of red colour on the surface is due to formation of iron oxide, but the red colour in the core resulting from formation of cuprite mineral. Layered corrosion is the main corrosion form of the fragments. Some parts lost from the coin surface. The interior layers were formed with silver and cuprite. Fragment is in worst state, because it’s completely oxidized. Figure 3: schematic of corrosion layer stratigraphy

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B. SEM-EDS results SEM examination and EDS analyses display the morphology and microstructure of billon corrosion compounds covering the coin surfaces and soil deposits. FIGURE 4: SEM images of samples from billon coin fragments A) SEM Mapping of Patina made up from silver and copper corrosion compounds, B) SEM Mapping of billon coin surface fretting damage, C) SEM image of bassanite crystals resulting from soil deposits, D) SEM of soil encrustations on the coin surface, E) SEM mapping of the soil deposits on the coin surface, F) SEM image showing black spot of corrosion compounds on the coin surface, G) SEM-EDS result of the soil deposits on the coin surface, H) SEM image showing surface porousity resulting from corrosion compounds of Ag-Cu metals I) SEM image shows dendritic structure of silver surrounding corrosion products, J) SEM image shows mass of silver covering by corrosion products

A B

C D

E F

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G H

I J Figure 4-A and 4-B show elemental mapping that indicates the high percentage of silver-copper. From EDS result, silver concentration is nearly twice of copper in bulk and white spot. Sodium, calcium, Aluminum and magnesium were found as surficial deposits of billon coins, but iron was not detected. Phosphorus was detected on the surface caused by ancient organic remains of vegetation and animals. As shown in figure 4-C and 4-D, there is a high percentage of soil deposits on the billon coin surface were declared as sulpher, calcium, iron and silicon are detected. Sulphure and calcium are detected in high percentage but sodium, magnesium, silicon, potassium and aluminum in percentage low. SEM image result shows bassanite crystals (semi-hydrate gypsum) that adhered with the corrosion compounds resulting from the burial environment. Figure 4-E SEM mapping shows the corrosion compounds on the coin surface that was subjected to degradation phenomena during the burial environment. From EDS result, we conclude that silver is considered the major element in the white areas. In the figure 4-F, we can see the soil deposits in close contact with coin surface. Also, EDS data of the same sample reveals that sodium is the main element in black spot. The chemical active of sodium caused porousity on the surface. Figure 4-G shows halite crystals on the billon coin surface resulting from salt-rich sediments. SEM signifies a deep crack on the surface. Silver and copper corrosion compounds are detected as traces. From EDS results in table 4, Na and Cl elements are detected in high level, but chloride is greater than sodium. Figure 4-H shows SEM image result of the coin surface that reveals high level of copper corrosion products. Sodium and iron are detected in high level on the coin surface. SEM image declares localized corrosion that penetrates inside the coins. Figure 4-I clarifies the dendritic form that is the proof of minting method by casting method. Also, EDS shows the high percentage of silver, but copper are not included. Other elements were declared in high level with silver as sulpher and iron. Figure 4-J clarifies limit metal residue that contains the main elements of billon alloy. The residual metal in this area contains 77.19(wt)% by mass of silver and 3.84% mass of copper, because of its chemically active that caused transformation into corrosion products. In the following table 4, EDS result reveals the wide variation of the chemical composition of the billon coin combined with soil minerals.

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Table 4: EDS analyses of samples from billon coin fragments Sample % Α Β C D E F G H I J Element Na 11.34 10.46 1.91 1.46 7.49 70.20 34.21 9.65 1.92 1.23 Mg 1.69 1.99 1.57 0.42 1.60 2.75 0.98 1.46 2.32 1.63 Al 1.06 0.77 1.52 0.87 0.89 2.95 0.89 0.71 0.74 1.61 Si 1.45 .0.95 1.93 3.06 1.03 ----- 0.74 ------0.62 1.29 S 0.77 ------34.58 33.37 1.45 ------1.02 ------9.42 0.86 P 0.87 ------0.65 ------Cl 0.48 0.26 1.77 3.16 0.45 2.74 58.56 0.77 0.65 0.60 Ag 52.95 55.86 1.66 0.74 78.73 2.85 0.66 7.18 66.53 77.19 K ------0.76 0.59 ------3.75 0.18 0.71 0.14 0.35 Ca 0.87 0.74 39.63 42.35 0.51 3.56 0.61 0.49 2.21 0.30 Fe ------14.57 13.67 ------1.46 5.86 15.45 9.42 Cu 28.47 28.97 ------0.31 7.20 11.20 0.69 73.12 ----- 5.52 C. X-RD result X-ray powder diffraction data of bulk samples revealed the composition of the corrosion layered encrustations and soil deposits. Table 1 X-RD results of two samples (A and B) from the random corrosion products of the billon coins combined with soil deposits ° ° Angle 2Θ d (A ) I/I0 Angle 2Θ d (A ) I/I0 4.35 20.32 14.6 5.46 16.17 22.5 6.74 13.11 22.2 6.11 14.46 18.0 7.87 11.22 15.6 8.09 10.92 25.6 10.09 8.76 20.5 10.69 8.27 20.8 12.41 7.13 16.1 13.02 6.80 14.9 14.80 5.98 17.1 14.75 5.46 23.8 16.17 5.48 72.8 16.23 5.08 91.3 17.03 5.21 21 17.71 5.02 26.3 17.89 4.96 17.1 22.32 3.98 10.5 31.48 2.84 65.4 24.92 3.58 10.8 32.21 2.78 97.5 32.30 2.78 96.2 33.52 2.67 23.4 39.68 2.27 100.0 36.46 2.46 56.5 42.39 2.13 21.9 39.62 2.27 100 50.17 1.82 59.6 42.22 2.14 33.6 53.58 1.71 23.1 47.92 1.90 38.2 49.98 1.82 32.1 53.34 1.72 22.8 57.06 1.61 10.6 A B

From the previous results illustrated in table 1 (A and B), d (A°) value and 2Θ peak positions extracted manually from the reference pattern. When 2 were 32.21°A, chlorargyrite (AgCl) was known, but acanthite was detected at 49.98°A and argentite was detected at 49.98°A. The peaks of were known at 16.17°A and 39.62°A. Generally, average errors in 2Θ and/or d (A°) ranged from 0.1 and 0.2. Figure 13: The percentage of the corrosion compounds and soil deposits

A B Figure 13-A and 13-B shows billon patina that was constituted of cuprite, atacamite, chlorargyrite and in high level. Akagneite, halite and iron oxides were detected in low level in the external layer. Silver and copper sulphides were identified as acanthite, argentite, spionkopite, and brochantite. Atacamite is the highest corrosion compound in the random powder of billon alloy.

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Table 2: The minerals of corrosion compounds of billon coins Mineral Formula

Cuprite Cu2O

Atacamite CuCl2.3Cu(OH)2 Spionkopite CuS

Malachite CuCO3.Cu(OH)2

Atacamite CuCl2.3Cu(OH)2

Copper hydrogen phosphite hydrate CuHPO3.2H2O

Brochantite Cu4(SO4)(OH)6 chlorargyrite AgCl

Argentite Ag2S

Acanthite Ag2S Wustite FeO

Hematite Fe2O3 Akaganite FeO(OH,Cl)

Siderite FeCO3 Lepidocrocite γ-FeOOH

Greenalite Fe23Si2O5(OH)4

Magnetite Fe3O4

Bassanite CaSO4.0.5H2O

VI. Discussion There is a strong consistent correlation between the kind of the corrosion products and surrounding environment. From the obtained results, sandy soil played an important role in their severe corrosion during burial incubation resulting from chloride ions. This soil structure is a porous that changes from sub saturation to saturation with water movement (Fjaestad, Nord and Tronter, 1997, Tylecate, 1979). Also, circulation of saline water in the soil had a serious effect on the coins, which led to transformation the ductile metals completely into corrosion products (Werner and Roland, 1998, Tennent and Antonio, 1981). The analysis and investigation revealed halite and bassanite adhering to the coin surface. Halite was the source of chloride ions that make copper and silver chlorides. The result obtained confirms the presence of the two main metals of billon alloy. Because copper is less noble than silver, the first metal corroded and dissolved more than the latter, so there is no residue of metallic copper in the billon coin surface, caused by the different potential of silver-copper during the electrochemical corrosion. The EDS and X-RD analysis result of the corrosion crust revealed a relatively high chloride content in the coins with very low content of sulfide. Generally, copper corrosion patina in billon alloy involves cuprite, paratacamite, chlorargyrite and atacamite. Cuprite appeared obviously from the cross section in the core of the billon coin. Metal chlorides have been formed during the long-term archaeological burial environments thus forming chloroargyrite, Cu[I] chloride and Cu [II] compounds and akaganiete were detected by XRD spectrum. In addition to, it must be taken into account that, iron and there oxides were identified by the investigation and analysis methods resulting from the original alloy. From XRD and EDS analyses results, Phosphorous and Copper hydrogen phosphite hydrate are detected in low level resulting from organic material in the burial soil. It can be deduced from the elongation of the silver grains and dendritic structure that the via casting method was used in the manufacture of the coins. This result confirms the hypothesis proposed by metallurgists (see figure14, 15). Figure 14: shows SEM image of silver in the Figure 15 The most phase of metals solidify with core of billon coin a dendritic structure

After: Ashby, and Jones, 1999

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VII. Conclusions The corrosion and metallurgy of excavated billon coins from Tell Basta have been identified and chracterised through a combination of stereo and scanning electron microscope with energy dispersive spectrometry and X-ray diffraction for mineral characterisation. Billon coins were excavated from the sandy soil in worse state, and they coalesced by corrosion products. The fragility of the coin resulted from the impact of high level of salts in the burial environment as halite and bassanite. Generally, corrosion products mainly consist of silver, copper and iron chlorides. The corrosion products are found in 4 layers, in addition the core of the coin consists of silver and cuprite. Neither the coin surface nor the core contains copper metal resulting from corrosion process during long periods of burial. It is found that the changing in the thickness, diameter, size and weight of the coins could be allowed measurement of corrosion rate. From EDS result, the average ratio of silver element is 57%, but the ratio of copper element is 29% on the surface. So, there is a difference between the ratio of copper and silver and their corrosion compounds in the exterior and interior layers. Chloride compounds as atacamite, paratacamite, botallacite, chlorargyrite, and akaganeite must be removed to prevent the activity of re-corrosion.

References [1] Alsaa’d, Z., Chemical Analysis of Some Umayyad Dirhems Minted at Wāsit, Journal of the Economic and Social History of the Orient, Vol. 42, No. 3, 1999, pp. 351 [2] Ashby, M., and Jones, D., Engineering Materials 2, An Introduction to Microstructures, Processing and Design, 2nd edn., Butterworth-Heinemann, Oxford, 1999 [3] Burns, D, Townshend, A., and Carter, A., Inorganic Reaction Chemistry, Reactions of the Elements and their compounds, Part A: Alkali Metals to Nitrogen, Ellis Horwood Limited, New York, 1981, p.158 [3] Bushman, J., Corrosion and Cathodic Protection Theory, Principal Corrosion Engineer Bushman & Associates, Inc Medina, Ohio USA, 2010 [4] Butcher, K., and Ponting, M., The Metallurgy of Roman Silver Coinage from the Reform of Nero to Reform of Trajan, Cambridge University Press, 2014, p.26,140 [5] Clayton, T., Metals Used in Coins and , 2013 http://www.cartage.org.lb/en/themes/arts/scultpurePlastic/NumismaticsSigillography/CoinsThroughHistory/MetalsUsed/MetalsU sed.htm. [6] Domoneand, J., and Jefferis, A., Structural Grouts, CRC Press, 2002 [7] Dracott, J., Piezoelectric printing and pre-corrosion, Electrical Resistance Corrosion Monitors for the conservation of heritage iron, PhD Thesis, Faculty of Engineering and Physical Sciences, School of Materials, Corrosion and Protection center, 2014, p.70 [8] Dunlap, M., Adaskaveg, J., Introduction to the Scanning Electron Microscope Theory, Practice, & Procedures, Facility for Advanced Instrumentation, U. C. Davis, 1997 [9] Escalante, E., Soils, in Corrosion Tests and Standard Application and Interpretation, 2nd edn., ASTM, USA, 2005 [10] Ferreira, C., Ponciana, J., Vaitsinan, D., and Pérez, D., Evaluation of the Corrosivity of the Soil Through its Chemical Composition, Science Direct, Science of the total Environment, 388, 2007, pp.250-255 [11] Fjaestad, M., Nord, G., Tronter, K., The Decay of Archaeological Copper Alloy Artifacts in Soil, in Metal 95, James LTD, London, 1997 [12] Gettens, R., The Corrosion Products of Metal Antiquities, Annual report Smithsonian Institute, Archeomaterials, Washington, DC, 1985 [13] Grassini, S, Angelini, E, Palumbo, F., and Ingo, G., Advanced Plasma Treatment for Cleaning and Protecting Artifacts, Proceedings: Strategies for Saving our Cultural Heritage, 2007, p.127 [14] Hamilton, D., Conservation of Metal Objects from Underwater Sites: A Study in Methods, Publication No.1, Texas Antiquities Committee, 1976 [15] Henderson, J., Metallurgical Dictionary, Reinhold Publishing Corporation, New York, 1953, p.36 [16] https://earth.google.com [17] Ii, S., Nano-scale Chemical Analysis in Various Interfaces with Energy Dispersive X-Ray Spectroscopy and Transmission Electron Microscopy, in “X-ray spectroscopy”, Croatia, 2011 [18] Kelly, R., Pitting in Corrosion Tests and Standards: Application and Interpretation, editor, Baboian, R., ASTM, USA, 2005 [19] Lucas, A., Copper in ancient Egypt, The Journal of Egyptian Archaeology, Vol. 13, No. 3, 1927, pp. 162-170 [20] MacLeod, I., and Schindelholz, E., Surface analysis of corroded silver coins from the wreck of the San Pedro De Alcantara (1786): Proceedings of Metal 2004 National Museum of Australia Canberra ACT, 2004, p.21 [21] Renfrew, C., and Bahn, P., Archaeology, Theories, Methods and Practice, 4th edition, Thames & Hudso, 2004 [22] Sato, N., Basics of Corrosion Chemistry, Green Corrosion Chemistry and Engineering: Opportunities and Challenges, edr., Sharma, S, 1st edn., Wiley-VCH Verlag GmbH & Co. KGaA, 2012, P.19 [23] Scheidel, W., (2010): Coin quality, coin quantity, and coin value in early China and the Roman world, Version 2, Stanford University [24] Seeley, N., Aims and Limitations in the Conservation of Coins, Numismatics and Conservation, Proceedings of a seminar held in November 1978 at the University of Durham, Durham, 1980 [25] Selwyn, L., Sirois, P., and Argyropoulos, V., The Corrosion of Excavated Archaeological Iron with Details on Weeping and Akaganeite, Studies in Conservation, Vol. 44, No.4, 1999, pp. 217-232 [26] Selwyn, L., Silver, In Metals and Corrosion, a handbook for the conservation professional. edr., Canadian Conservation Institute, Ottawa, 2004, pp.131–140. [27] Sharkey, J., and Lewin, S., Conditions Governing the Formation of Atacamite and Paratacamite, The American Mineralogist, Vol., 56, 1971, P.191 [28] Tennent, N., and Antonio, K., Disease Synthesis and Characterisations of Botallackite, Paratacamite, and Atacamite by Infrared Spectroscopy, ICOM Committee for Conservation, 6th Triennial Meeting, Ottawa, Paris, 1981

AIJRFANS 15-506; © 2015, AIJRFANS All Rights Reserved Page 8 Saleh and Megahed, American International Journal of Research in Formal, Applied & Natural Sciences, 13(1), December, 2015- February, 2016, pp. 01-09

[29] Thompson, F., and Chatterjee, A., The Age-Embrittlement of Silver Coins, Studies in Conservation, 1954, Vol. 1, No. 3, pp. 115- 126 [30] Turgoose, S., Post excavation changes in iron antiquities, Studies in Conservation, vol. 27, No 3, 1982, pp.97-101 [31] Tylecate, R., The Effect of Soil Corrosion on Long-Term Corrosion of Buried tin and Copper, Journal of Arch., Science, No. 4 1979 [32] Weil, P., Technical Art History and Archeometry I, Patina: Historical Scientific and Practical Considerations, Revista Brasileira de Arqueometria, Restauração e Conservação, Vol.1, No.2, 2007, pp.60 -66 [33] Werner, J., and Roland, B., Corrosive Decay of Archaeological Metal Finds from Different Soils and Effects of Environmental Pollution, Metal 48 proceeding of the International Conference on Metals conservation, France, 1998, pp.100-105 [34] Winefordner, D., X-Ray Fluorescence Spectrometry, Chemical Analysis, A Series of Monographs, in Analytical Chemistry, and its Applications, John Wiley & Sons, Vol.152 2012 [35] www.engr.sjsu.edu/MC2/SOP_EDAX.pdf [36] www.footdefense.com

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