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Neutron investigation of an exceptional zinc lamp from the Academia Georgica Treiensis archaeological collection (Italy) Massimo ROGANTE1*, Eszter HORVÁTH2, György KÁLI2, Zsolt KASZTOVSZKY3, Zoltán KIS3, Imre KOVÁCS4, Boglárka MARÓTI3, László ROSTA2, Zoltán SZŐKEFALVI-NAGY4 1 Rogante

Engineering Office for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences 3 Centre for Energy Research, Hungarian Academy of Sciences 4 IInstitute for Particle and Nuclear Physics, Wigner Research Centre, Hungarian Academy of Sciences * Correspondent author’s address: 62012 Civitanova Marche, Contrada San Michele, 61. ITALY, e-mail: info@roganteengineering.it

2 Institute

NINMACH 2013 The collection

The lamp

The Academia Georgica Treiensis is one of the oldest Italian Academies, created in the XV c. [1]. Its Archaeological Collection was put together by the noble family of Teloni, Counts in Treia, Italy, from the late XVIII until the late XIX c. The Collection has been recently reorganised and inventoried: it is composed of about 517 pieces, mostly of unknown origin, from the prehistoric and ancient periods. It contains different types of artefact, e.g. armours, metallic and ceramic table-ware, jewels, oil lamps, bricks and varied tools [2, 3].

A few metallic objects from this collection have been selected for a neutron based archaeometric investigation. The present case study is focussing on a lamp which proved to be unique in several aspects drawing more attention to its production and dating. The lamp is characterised with six radiating voluted nozzles of ogiveshape tip. Three of them are decorated with different bearded faces representing likely Silenus. Based on the type of the artefact as well as its supposed bronze material, it was considered as an ancient product from the Imperial Roman period.

Methodology – involved complementary techniques:

Research objectives

1) Prompt Gamma Activation Analysis (PGAA) Æ elemental bulk composition 2) Time-of-Flight Neutron Diffraction (TOF-ND) Æ phase bulk composition, texture 3) Neutron Radiography (NR) Æ 2D and 3D imaging, radiography-driven PGAA 4) external beam Particle Induced X-ray Emission (PIXE) Spectroscopy Æ elemental surface composition 5) Optical Microscopy (OM) Æ manufacture, usage

1) to identify the alloy composition of the object 2) to reconstruct the manufacture and usage of the object 3) to advance the accurate description of the object 4) to compare the results with the data of analogous archaeological material 5) to clarify the origin and date of the object

Results The neutron investigations allowed us to determine the bulk elemental composition, also providing a qualitative and quantitative assessment of the phase composition and the structural properties of the constituents, as well as radiographic images. The additional PIXE measurements served the quantitative analysis of major, minor and trace elements supplying data on the near-surface composition. The binocular microscope observation advanced the reconstruction of the manufacture and the usage of the lamp.

Analytical data

Technological observations

The obtained results showed that the base material of the lamp is not a bronze alloy – as previously supposed – but of metallic zinc. Based on the TOF-ND analyses the alloy contains an almost pure zinc phase, wherein only a very few amount of copper was detected as minor element. Apart from Zn and Cu, the PGAA and PIXE analyses identified some Sn, Pb and Fe content as well, however these constituents cannot be in solid solution with Zn. They possibly represent further phases such as impurities or remains of some soldering material, but certainly not alloying elements. unc unc unc unc unc Cu Sn Pb Fe Ni % % % % % PIXE (wt%) less corroded surface 88,65 0,65 2,61 2,24 3,35 36,92 4,88 4,39 0,48 6,41 tr

The optical microscopic examination revealed that although the lamp was cast, the applied technique is not the lost wax casting, typical for ancient bronze lamps. The lamp was cast in two pieces and then presumably joined by soldering. The joint is clearly visible on the side of the object, especially on those nozzles, where the upper part is damaged. However, at this joint no soldering material could be observed, possibly since the lamp is covered by a very thick corrosion layer. The natural greyish colour of the zinc appears only in a few spots. The details of the ornamentation point out the use of a poorly designed mould. Also the casting process was carried out carelessly resulting in cracks and deformations on one of the nozzles. The surface is very rough and as plenty of small bubbles indicate, it was not treated after the casting – no polishing or chasing was performed. The dark contours observed around the wick-holes show that the lamp was in use, the flame might deposit carbon residue.

PGAA (wt%) one of the nozzles

a

METHOD

LOCATION

Zn

87,23 1,10 0,76 10,00 3,89 6,00 7,77 10,00 0,35 10,00 -

TOF (wt%) upper part of the lamp 98,96 0,05 1,04 0,05

-

-

-

-

-

-

b

c

d

e

f

-

Compositions of the investigated lamp – elemental composition: PIXE, PGAA; phase composition: TOF The TOF-ND analysis pointed out that the amount of the copper is nearly the maximum solubility. No significant amount of other phase was measurable (neither other metals nor epsilon brass).

a) and d) side-view of the nozzles; b) untreated surface of the lamp; c) and e) the damaged and the deformed nozzles; f) thick corrosion layer with some greyish spots of the original surface

Discussion

d e d) PIXE spectrum of the lamp; e) The raw TOF-ND spectrum and the fitted peak positions. The anisotropic torsion of the unit cell (Δa/a0=+0.0015, Δc/c0=-0.0038) indicates that the solute atom is copper.

The presence of zinc among the alloying elements is of great significance as the way of its use may indicate the possible earliest date of the production [4]. High pure zinc is an unexpected base material from the classical antiquity. Due to the high volatility of metallic zinc and the reactivity of the zinc vapour, producing zinc metal was a technological challenge before the industrial discoveries in the early modern period. Considering the few historical and archaeological sources relevant to the ancient and medieval metallurgical processes, until the early XIX c. metallic zinc could have been available only as a by-product of the zinc-rich lead ores smelting [5, 6]. However, the amount of the gained zinc was practically insufficient for manufacturing large objects. Hence, in case of the investigated lamp, compositional data query the ancient production and genuineness raising other hypotheses about the origin. Also the technical details of the casting process argue against the ancient date of the lamp. The use of the two-piece mould instead of the lost wax casting suggests a modern, XIX c. product [7].

Conclusions

References

a b c The lamp during the (a) PIXE and (b) PGAA investigation; c) NR image of one of the nozzles of the lamp

The identification of the compositional and technological details clarified the date and origin of the lamp. The metallic zinc raw material and the two-piece mould applied in the casting revealed that this artefact is not an archaeological object from the Imperial Roman period but a pastiche from the XIX c. reflecting in style and shape the Roman lamps, realised mainly in bronze and pottery.

[1] F. Benigni, L'Accademia georgica di Treja nella relazione del dott. Fortunato Benigni, Public dissertation, Nov. 25, 1778, Academia Georgica Treiensis, Fonti per la storia delle Marche, Regia Deputazione di storia patria per le Marche, Fabriano, Italy (1939), pp. 171-192. [2] E. Stortoni, Il collezionismo privato come forma di cultura sommersa: l'esempio della raccolta archeologica presso l'Accademia Georgica di Treia, in: Le Marche: la cultura sommersa tra Ottocento e Novecento”, Atti, II, Convegno di Studi, Treia, 8 - 9 novembre 1997 e 7 novembre 1998, Accademia Georgica – Treia, Macerata (2000), pp. 375-388. [3] E. Stortoni, La collezione archeologica Teloni presso l’Accademia Georgica di Treia, in: Beni archeologici della provincia di Macerata, G. M. Fabrini, G. Paci, R. Perna (Eds.), Pescara (2004), pp. 161-163. [4] D. R. Hook & P. T. Craddock, The Scientific Analysis of the Copper-alloy Lamps: Aspects of Classical Alloying Practices, The project has received funding from the European 7th Framework Programme. Financial support by the in D. M. Bailey: A Catalogue of the Lamps in the British Museum IV. London (1996), pp. 144-163. Access to Research Infrastructures activity in the 7th Framework Programme of the EU (CHARISMA Grant [5] P. T. Craddock, Zinc in Classical Antiquity, in P. T. Craddock (Ed.): 2000 Years of Zinc and Brass, London (1998), pp. 1-6. Agreement n. 228330) is gratefully acknowledged. The authors are grateful to Prof. emeritus Paul Craddock [6] P. T. Craddock, Scientific Investigation of Copies, Fakes and Forgeries, Oxford 2009. [7] D. M. Bailey: A Catalogue of the Lamps in the British Museum IV. London (1996), pp. 123-124. and Prof. Enzo Catani for references, conversations and communications on various aspects of this issue.

Acknowledgements
































































































 











































































The Academia Georgica Treiensis is one of the oldest Italian Academies, created in the XV century for the main interests of poetry and literature. In the XVIII century, influenced by the Enlightenment ideas, the Academy decided to renovate its interests “encouraging rational and practical studies to improve agriculture and industry and to honour sciences, literature and arts� [1]. The Archaeological Collection of Academia Georgica Treiensis was put together by the noble family of Teloni, Counts in Treia, Italy, between the end of the XVIII and the end of the XIX century. The Collection has been recently reorganized and inventoried: it is composed of about 517 pieces (e.g. armours, table-ware, jewels, ceramics and varied tools), mostly of unknown origin but belonging to prehistoric and ancient periods, nevertheless it is not excluded that some objects are earlier [2, 3]. A few metallic objects from this collection have been selected for a neutron based archaeometric investigation. The primary goal of the analyses was to advance the accurate technological and material description of the objects providing scientific data for a further and more comprehensive comparative analysis also covering the find material from the close archaeological sites [4, 5]. The involved complementary techniques are Prompt Gamma Activation Analysis (PGAA), Time-of-Flight Neutron Diffraction (TOF-ND) and Neutron Radiography (NR). The neutron investigations allowed us to determine the bulk composition, also providing a qualitative and quantitative assessment of the phase composition and the structural properties of the constituents, as well as radiographic images, finally to identify possible manufacturing techniques. An additional examination, carried out by external beam particle induced X-ray emission (PIXE) spectroscopy, provided a quantitative analysis of major and trace elements and supplied data on the near-surface elemental composition complementary to the results characteristic for the bulk. The present case study is focussing on one of the investigated objects, a not common, so called polilicnes lamp, which proved to be unique in several aspects drawing more attention to its production and dating. The lamp is characterised with six ogive-shaped projections of which three are decorated with different bearded faces. Based on the type of the artefact as well as its supposed bronze material, it was considered as an ancient product from the Imperial Roman period. The obtained results, however, showed surprisingly that it is mainly made of metallic zinc. It raises several questions, since this material is not to be expected from the classical antiquity. Because of the high volatility of metallic zinc and the reactivity of the zinc vapour, producing zinc metal was a technological challenge before the industrial discoveries of the early modern period. Considering the few relevant historical and archaeological sources about the ancient and medieval metallurgical processes, metallic zinc could be available until the beginning of the XIX century only as a byproduct of the zinc-rich lead ores smelting [6, 7]. The gained zinc, however, could be of a very small amount practically insufficient for manufacturing large objects. With respect to metallic artefacts from archaeological periods, the presence of zinc among the alloying components (both in brass and zinc objects) is of great significance as the way of its use may indicate the possible earliest date of the production. In the case of the polilicnes lamp the identified elemental and phase composition, i.e. the high pureness of the zinc material, opens different hypotheses about its origin querying its ancient production and genuineness. With the archaeological interpretation of the analytical results we aimed to clarify and reconstruct the context


and history of this peculiar piece belonging to the investigated collection. References [1] F. Benigni, L'Accademia Georgica di Treja nella relazione del dott. Fortunato Benigni, Public dissertation, Nov. 25, 1778, Academia Georgica Treiensis, Fonti per la storia delle Marche, Regia Deputazione di storia patria per le Marche, Fabriano, Italy (1939), pp. 171-192.

[2] E. Stortoni, Il collezionismo privato come forma di cultura sommersa: l'esempio della raccolta archeologica presso l'Accademia Georgica di Treia, in: Le Marche: la cultura sommersa tra Ottocento e Novecento”, Atti, II, Convegno di Studi, Treia, 8 - 9 novembre 1997 e 7 novembre 1998, Accademia Georgica – Treia, Macerata (2000), pp. 375-388. [3] E. Stortoni, La collezione archeologica Teloni presso l’Accademia Georgica di Treia, in: Beni archeologici della provincia di Macerata, G. M. Fabrini, G. Paci, R. Perna (Eds.), Pescara (2004), pp. 161-163. [4] M. Rogante, Zs. Kasztovszky, A. Manni, Prompt Gamma Activation Analysis of bronze fragments from archaeological artefacts, Matelica Picenum necropolis, Italy, Notiziario Neutroni e Luce di Sincrotrone, 15/1 (2010), pp. 12-23. [5] M. Rogante, G. De Marinis, Zs. Kasztovszky, F. Milazzo, Comparative analysis of Iron Age bronze archaeological objects from a Picenum necropolis of Centre Italy with Prompt Gamma Activation Analysis, Nuovo Cimento C, 30/1 (2007), pp. 113-122. [6] P. T. Craddock, Zinc in Classical Antiquity, in: 2000 Years of Zinc and Brass, P. T. Craddock (Ed.), London (1998), pp. 1-6. [7] P. T. Craddock, Scientific Investigation of Copies, Fakes and Forgeries, Oxford 2009. Primary authors : Dr. ROGANTE, Massimo (Rogante Engineering Office) Co-authors : Dr. MITCSENKOV-HORVÁTH, Eszter (Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences) ; Dr. KÁLI, Gyorgy (Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences) ; Dr. KASZTOVSZKY, Zsolt (Centre for Energy Research, Hungarian Academy of Sciences) ; Dr. KIS, Zoltán (Nuclear Analysis and Radiography Department, Centre for Energy Research, Hungarian Academy of Sciences) ; Dr. KOVÁCS, Imre (Institute for Particle and Nuclear Physics, Wigner Research Centre, Hugarian Academy of Sciences) ; Dr. MARÁTI, Boglárka (Centre for Energy Research, Hungarian Academy of Sciences) ; Prof. ROSTA, László (Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences) ; Prof. SZÕKEFALVI-NAGY, Zoltán (Institute for Particle and Nuclear Physics, Wigner Research Centre, Hugarian Academy of Sciences) Presenter : Dr. ROGANTE, Massimo (Rogante Engineering Office)




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