Pin HR-3071 - Tin Bronze - Late Bronze Age - Switzerland

Pin HR-3071 - Tin Bronze - Late Bronze Age - Switzerland

Pin HR-3071

Naima. Gutknecht (HE-Arc CR, Neuchâtel, Neuchâtel, Switzerland) & Rémy. Léopold (HE-Arc CR, Neuchâtel, Neuchâtel, Switzerland) & Domon Beuret. Emmanuelle (Laténium, Neuchâtel, Neuchâtel, Switzerland)

Contact the author Share Print
/artefacts/1366/
Credit Laténium, C.Cevey.

Fig 1: Pin with decorated head and round section,

Credit HE-Arc CR, N.Gutknecht/L.Rémy

Fig. 2: Green corrosion products (detail) around the head of the pin,

Credit HE-Arc CR, N.Gutknecht/L.Rémy

Fig. 3: Dense and smooth olive green corrosion products (detail) on the middle of the pin with lacunas showing the underlying metal,

Pin with decorated head and round section. Locally a dense and smooth olive green stratum is preserved, while green corrosion products develop on the underlying metal (Figs. 1-3). Dimensions: L = 19.0cm; WT = 12.4g.

Jewellery

Hauterive - Champréveyres, Neuchâtel, Neuchâtel, Switzerland

Excavation 1983-1985, object from layer 1

Late Bronze Age

Lake

Laténium, Neuchâtel, Neuchâtel

Laténium, Neuchâtel, Neuchâtel

HR-3071

None.

Complementary information

The object was analyzed in 1987 by Schweizer. Documentation of the strata in binocular mode of the object was performed in 2022.

Credit HE-Arc CR, N.Gutknecht/L.Rémy

Fig. 4: Sides A and B (opposite sides) of the pin showing the XRF analysis areas (red circles),

The schematic representation below gives an overview of the corrosion structure encountered on the pin from a first visual macroscopic observation.

Strata Type of stratum Principal characteristics
CP1 Corrosion product Light green, thin, scattered, non compact, very soft
CP2 Corrosion product Dark green, thin, scattered, compact, very soft
CP3 Corrosion product Dark brown, medium, discontinuous, compact, hard
CP4 Corrosion product Olive green, medium, discontinuous, compact, hard
M1 Metal Yellow, metallic, compact, hard

Table 1: Description of the principal characteristics of the strata as observed under binocular and described according to Bertholon's method.

Credit HE-Arc CR, N.Gutknecht.

Fig. 5: Stratigraphic representation of the corrosion structure of the pin by macroscopic and binocular observation using the Micorr application with reference to Figs. 6 and 7,

Fig. 6: Stratigraphic representation of the corrosion structure of the head of the pin (Fig. 2) observed macroscopically under binocular microscope using the MiCorr application with reference to Fig. 5. The characteristics of the strata, such as the discontinuity, are accessible by clicking on the drawing that redirects you to the search tool by stratigraphy representation, Credit HE-Arc CR, N.Gutknecht.
Fig. 7: Stratigraphic representation of the corrosion structure of the middle of the pin (Fig. 3) observed macroscopically under binocular microscope using the MiCorr application with reference to Fig. 5 where CP1 stands for CP4. The characteristics of the strata, such as the discontinuity, are accessible by clicking on the drawing that redirects you to the search tool by stratigraphy representation, Credit HE-Arc CR, N.Gutknecht.

No sample has been taken. The observation and analysis were performed directly on the object.

Tin Bronze

None

85-194

None

None

Complementary information

None.

Analyses performed:

Non-invasive approach

XRF with handheld portable X-ray fluorescence spectrometer (NITON XL5). General Metal mode, acquisition time 60s (filters: Li20/Lo20/M20).

XRF analysis was carried out on two representative areas of the surface (Fig. 4). Point 1 was performed on a lacuna of the olive green corrosion layer and point 2 on the olive green corrosion layer (CP4 of Fig. 5).

The metal is presumably a tin bronze alloy with proabably some Sb and As and traces of Pb and Ag. The other elements detected are: S, Fe, Si, Zn.

Results of point 2 are very different from those of point 1, they indicate the enrichment in Fe and in S and depletion in Cu.

Elements
(mass %)

 Cu Sn S Fe
 Sb As
 Pb
 Ag Si
 Zn
 Total
   % +/- 2σ % +/- 2σ % +/- 2σ  % +/- 2σ % +/- 2σ % +/- 2σ % +/- 2σ % +/- 2σ % +/- 2σ % +/- 2σ  
1 87.0 0.2 8.5 0.05 1.5 0.04 0.2 0.01 0.9 0.02 0.7 0.03 0.4 0.02 0.3 0.01 0.2 0.06 0.1 0.03 99.8
2 36.5 0.1 4.0 0.02 25.0 0.08 32.0 0.09 0.5 0.01 0.2 0.01 0.1 0.01 0.2 0.01 0.5 0.04 0.1 0.02 99.1

Table 2: Chemical composition of the surface of the pin at two representative areas shown in Fig. 5. Method of analysis: XRF.

None.

None

Cu

Sn

Complementary information

None.

CP4 (dense, smooth olive green stratum) is enriched with Fe and S and depleted in Cu. It seems to correspond to chalcopyrite (CuFeS2).

Multiform

lake patina (Schweizer 1994)

Complementary information

In the article "Bronze objects from Lake sites: from patina to bibliography. In: Ancient and historic metals, conservation and scientific research" (Schweizer 1994), the corrosion products of the pin 3071 (LAB MAH 85-194) were analysed with XRD. The results show that the pin contains sulfosalt (sinnerite Cu6As4S9) and copper carbonate (malachite Cu2(CO3)(OH)2) as well as copper iron sulfide (chalcopyrite CuFeS2). Sinnerite appears as dark cristals, malachite as green cristals and chalcopyrite as a brown smooth layer.

The corrosion structure has only been documented in binocular mode (Figs. 6 & 7).

The pin is made from a tin bronze with possibly some Sb and As. It has been extensively documented by Schweizer to establish the lake and terrestrial patina typologies in his research paper from 1994. Chalcopyrite indicates a lake patina that was generated by the presence of sulfato-reducing bacteria in the burial environment and copper carbonate refers to a terrestrial patina.

References on object and sample

Object files in MiCorr

1.    MiCorr_Pin or needle fragment HR-3031
2.    MiCorr_Tang fragment of a knife HR-6567
3.    MiCorr_Tang fragment of a knife HR-6246
4.    MiCorr_Pin HR-18152
5.    MiCorr_Pin HR-17773
6.    MiCorr_PIN HR-18603
7.    MiCorr_Pin HR-3389

References object
8. Rychner-Faraggi A-M. (1993) Hauterive – Champréveyres 9. Métal et parure au Bronze final. Archéologie neuchâteloise, 17 (Neuchâtel), pl. 61/65.
9. Hochuli, S. et al. (1988) SPM III Bronzezeit , Verlag Schweizerische Gesellschaft für Ur- und Frühgschichte Basel, 76-77, 379.

References sample
10. Empa Report 137 695/1991, P.O. Boll.
11. Rapport d'examen, Lab. Musées d'Art et d'Histoire, Geneva GE, 87-194 à 87-197.
12. Schweizer, F. (1994) Bronze objects from Lake sites: from patina to bibliography. In: Ancient and historic metals, conservation and scientific research (eds. Scott, D.A., Podany, J. and Considine B.B.), The Getty Conservation Institute, 33-50.

References on analytic methods and interpretation

13. Robbiola, L., Blengino, J-M., Fiaud, C. (1998) Morphology and mechanisms of formation of natural patinas on archaeological Cu-Sn alloys, Corrosion Science, 40, 12, 2083-2111.