Sickle AUV-313 - Bronze - Late Bronze Age - Switzerland

Sickle AUV-313 - Bronze - Late Bronze Age - Switzerland

Sickle AUV-313

Rémy. Léopold (HE-Arc CR, Neuchâtel, Neuchâtel, Switzerland)

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Credit HE-Arc CR, L.Rémy.

Fig. 1: Sickle (side A) with a groove on the external front side and lacunas of the corrosion layers all over the surface,

Credit HE-Arc CR, L.Rémy.

Fig. 2: Brown-yellow and dark-grey corrosion products and lacunas of the corrosion layers (detail) of the haft of the sickle,

Credit HE-Arc CR, L.Rémy.

Fig. 3: Magenta-blue and brown-yellow corrosion products (detail) of the haft of the sickle,

Credit

Fig. 4: Brown-yellow and dark-grey corrosion products (detail) of the middle of the sickle,

Credit HE-Arc CR, L.Rémy.

Fig. 5: Brown-yellow and dark-grey corrosion products as well as lacunas of the corrosion layers (detail) of the tip of the sickle,

Sickle with a groove on the external front side with brown-yellow/dark-grey corrosion products as well as lacunas of the corrosion layers (Figs. 1-5). Dimensions: L = 13.67cm; Ømax. = 3.0cm; WT = 89.38g.

Tool

Auvernier, Neuchâtel, Switzerland

Excavation 1971

Late Bronze Age

Lake

Laténium, Neuchâtel, Neuchâtel

Laténium, Neuchâtel, Neuchâtel

AUV 313

No conservation data available, but a coating and inventory number is visible on the surface.

Complementary information

The object was documented in 1987 by Valentin Rychner. Documentation of the strata in binocular mode on the object was performed in 2022. 

Credit HE-Arc CR, L.Rémy.

Fig. 6: Sides A and B (opposite sides) with indication of XRF analyses (red circles) and location of Fig. 7 (blue square),

Credit HE-Arc CR, L.Rémy.

Fig. 7: Side view of a lacuna with the mention of the different strata,

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

 

Stratum Type of stratum Principal characteristics
CP1 Corrosion product Brown, pearly, thin, discontinuous, compact, brittle, very soft 
CP2 Corrosion product Extra light grey, matte, thin, discontinuous, compact, powdery, soft
CP3 Corrosion product Black, matte, thin, discontinuous, compact, powdery, very soft
M1 Metal Yellow, thick, metallic, continuous, compact, tough, very 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, L.Rémy.

Fig. 8: Stratigraphic representation of the corrosion structure of the sickle by macroscopic and binocular observation with indication of the corrosion structure used to build the MiCorr stratigraphy of Fig. 9 (red square),

Fig. 9: Stratigraphic representation of the corrosion structure of the sickle observed macroscopically under binocular microscope using the MiCorr application with reference to Fig. 8. The characteristics of the strata, such as discontinuity, are accessible by clicking on the drawing that redirects you to the search tool by stratigraphy representation, Credit HE-Arc CR, L.Rémy.

None.

Bronze

None

None

None

Complementary information

None. 

Analyses performed:

Non-invasive approach

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

The XRF analyses of the sickle were carried out on seven representative areas (Fig. 6). Points 1 and 2 were done in the brown corrosion layer of each side (CP1), points 3 and 4 on yellow areas covered with dark-grey corrosion layer (CP2 and CP3), points 5 and 6 on the magenta-blue corrosion layer (CP1), and point 7 on a black corrosion layer (CP1). All strata (soil, corrosion products, and metal) are analyzed at the same time.

The metal is presumably a tin bronze alloy with some As, Sb and Pb.  The other elements detected are : Fe, S, Si, Al, Zn and Ag (points 3 and 4).

Results of points 1, 2, 5, 6 and 7 are different and indicate the depletion in Cu and Sn and the enrichment in Fe and S.

 

Elements (mass %) Cu Fe S Sn
 Si Al Sb Zn Pb As Ag  
  % +/-2σ % +/-2σ % +/-2σ % +/-2σ % +/-2σ % +/-2σ % +/-2σ % +/-2σ % +/-2σ % +/-2σ % +/-2σ TOTAL
1 54.7 0.09 17.7 0.06 20.1 0.05 3.9 0.02 2.0 0.05 0.7 0.09 0.3 0.01 0.3 0.02 <LD <LD <LD <LD <LD <LD 99.7
2 51.4 0.07 17.2 0.05 26.6 0.05 3.6 0.02 0.4 0.02 0.3 0.07 0.3 0.01 0.1 0.01 <LD <LD <LD <LD <LD <LD 99.9
3 81.4 0.17 1.2 0.03 3.9 0.05 8.0 0.05 2.9 0.1 <LD <LD 0.5 0.02 <LD <LD 0.6 0.02 0.7 0.03 0.1 0.01 99.3
4 83.4 0.12 0.2 0.01 2.3 0.03 8.3 0.04 3.0 0.08 0.2 0.1 0.5 0.01 <LD <LD 0.6 0.02 0.8 0.03 0.1 0.01 99.4
5 52.5 0.08 17.8 0.05 25.1 0.05 2.9 0.02 0.9 0.03 0.4 0.07 0.2 0.01 0.1 0.01 <LD <LD <LD <LD 0.1 0.01 100.0
6 52.4 0.08 17.4 0.06 24.5 0.05 4.3 0.02 0.5 0.02 0.3 0.07 0.3 0.01 0.1 0.01 <LD <LD <LD <LD 0.1 0.01 99.9
7 51.4 0.08 18.7 0.05 25.2 0.05 3.3 0.02 0.6 0.03 0.4 0.07 0.3 0.01 0.1 0.01 <LD <LD <LD <LD 0.1 0.01 100.1


Table 2: Chemical composition of the surface of the pin at seven representative points shown in Fig. 6, Method of analysis: XRF, UR-Arc CR.

None.

None

Cu

Sn

Complementary information

Rychner (1987) indicates that the metal of the object is bronze. 

The appearance of CP1 and its composition (Cu, Fe, S) seem to indicate that it is either itaite or chalcopyrite.

Uniform

lake patina (Schweizer 1994)

Complementary information

According to Rychner (1987), the surface of the object is covered with itaite (Cu5FeS6).

The corrosion structure has only been documented in binocular mode (Fig. 9).

The sickle is made from a tin bronze. The XRF analysis show that the brown, purple and black corrosion layers (CP1) have higher %Fe and %S and lower % Cu and %Sn than the layer closer to the metal. It would indicate that CP1 is made of copper iron sulfide like itaite (Cu5FeS6) or chalcopyrite (CuFeS2) as described by Rychner (1987). According to Schweizer's paper from 1994, it would mean that CP1 could be a lake patina which was generated on the metal by the presence of sulfate-reducing bacteria in the burial environment.

References on object and sample

Object files in MiCorr

1.    MiCorr_Sickle Auv-310
2.    MiCorr_Sickle Auv-322
 

References object

3. Rychner, V. (1987) Auvernier 1968-1975: le mobilier métallique du Bronze final Formes et techniques. In: Cahiers d´archéologie romande 37, Auvernier 6. 39-40.
4. Rapport d'examen, Lab. Musées d'Art et d'Histoire, Geneva GE, 87-194 à 87-197.
5. 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, 143-157.