1. QUANTIFICATION OF SMITHING ACTIVITIES BASED ON THE INVESTIGATION OF SLAG AND OTHER MATERIAL REMAINS Vincent Serneels Sébastien Perret Mineralogy and Petrography Departement of Geoscience University of Fribourg Switzerland vincent.serneels@unifr.ch sebastien.perret@unifr.ch www.unifr.ch/mineral/archmet

2. The Production Line of the Ancient Iron Metallurgy V. Serneels, S. Perret Mineralogy and Petrography - University of Fribourg Production line : Sequence of technical steps from the raw material to the finished object.

3. The Production Line of the Ancient Iron Metallurgy V. Serneels, S. Perret Mineralogy and Petrography - University of Fribourg Natural ore Extracted ore Extraction Refuse

4. The Production Line of the Ancient Iron Metallurgy V. Serneels, S. Perret Mineralogy and Petrography - University of Fribourg Natural ore Extracted ore Extraction Refuse Concentrated ore Processing Refuse

5. The Production Line of the Ancient Iron Metallurgy V. Serneels, S. Perret Mineralogy and Petrography - University of Fribourg Natural ore Extracted ore Extraction Refuse Concentrated ore Processing Refuse Raw iron Reduction Slag Direct method of reduction : Bloomery process Solid state FeO + CO  Fe + CO 2

6. The Production Line of the Ancient Iron Metallurgy V. Serneels, S. Perret Mineralogy and Petrography - University of Fribourg Natural ore Extracted ore Extraction Refuse Concentrated ore Processing Refuse Raw iron Reduction Slag Direct method of reduction : Bloomery process Solid state FeO + CO  Fe + CO 2

7. The Production Line of the Ancient Iron Metallurgy V. Serneels, S. Perret Mineralogy and Petrography - University of Fribourg Natural ore Extracted ore Extraction Refuse Concentrated ore Processing Refuse Raw iron Reduction Slag Finished object Smithing Slag Plastic deformation (hammering / heating) Welding Heat treatment (annealing / quenching) Control of oxydation / carburization

8. Smithing V. Serneels, S. Perret Mineralogy and Petrography - University of Fribourg Smithing depends on : Quality of the metal Physical characteristics : Compact / homogenous bar iron Uncompacted / heterogeneous bloom iron Small pieces scrap Chemistry : % carbon % other elements : P, S, N, Mn, Ni, 0...

9. Smithing V. Serneels, S. Perret Mineralogy and Petrography - University of Fribourg Smithing depends on : Quality of the metal Type of object to produce Kind of object : Simplenail Complexcomposite blade iron + steel Size of object : Smallnail 10 g knife 100 g axe 1000 g Largeanchor 10000 g Sharpening, polishing, decoration

10. Smithing V. Serneels, S. Perret Mineralogy and Petrography - University of Fribourg Smithing depends on : Quality of the metal Type of object to produce Know-how of the smith Qualification : Heat treatments - annealing - quenching Welding etc...

11. Smithing slags V. Serneels, S. Perret Mineralogy and Petrography - University of Fribourg Contribution to slag formation : Hot oxidation  FeO Related to time / temperature Related to the size of the section Formation of a slag rich in iron oxides :

12. Smithing slags V. Serneels, S. Perret Mineralogy and Petrography - University of Fribourg Contribution to slag formation : Hot oxidation  FeO Formation of a slag rich in iron oxides : Related to time / temperature Related to the size of the section

13. Smithing slags V. Serneels, S. Perret Mineralogy and Petrography - University of Fribourg Contribution to slag formation : Hot oxidation  FeO Poorly consolidated metal  Fe Formation of a slag with iron particles :

14. Smithing slags V. Serneels, S. Perret Mineralogy and Petrography - University of Fribourg Formation of a slag rich in silica :Contribution to slag formation : Hot oxidation  FeO Poorly consolidated metal  Fe Use of flux  SiO 2

15. Smithing slags V. Serneels, S. Perret Mineralogy and Petrography - University of Fribourg Other elements participate with various chemical elements : Contribution to slag formation : Hot oxidation  FeO Poorly consolidated metal  Fe Use of flux  SiO 2 Other effects  K 2 O, CaO, SiO 2, Al 2 O 3...

16. Smithing slags V. Serneels, S. Perret Mineralogy and Petrography - University of Fribourg PCB : Plano-convex bottom slags Characteristic morphology Most typical smithing residue

17. Smithing slags V. Serneels, S. Perret Mineralogy and Petrography - University of Fribourg PCB : Plano-convex bottom slags Characteristic morphology Most typical smithing residue 1 cooling structure  Formed between lighthing and extinguishing of the fire 1 unit of work  1 day ?

18. Smithing slags V. Serneels, S. Perret Mineralogy and Petrography - University of Fribourg Variability of PCB slags : Dimensions and weight As a general rule : The weight is proportional to the quantity of work

19. Smithing slags V. Serneels, S. Perret Mineralogy and Petrography - University of Fribourg Variability of PCB slags : Dimensions and weight Shape

20. Smithing slags V. Serneels, S. Perret Mineralogy and Petrography - University of Fribourg Variability of PCB slags : Dimensions and weight Shape

21. Smithing slags V. Serneels, S. Perret Mineralogy and Petrography - University of Fribourg Variability of PCB slags : Dimensions and weight Shape Composition

22. Smithing slags V. Serneels, S. Perret Mineralogy and Petrography - University of Fribourg

23. Smithing slags V. Serneels, S. Perret Mineralogy and Petrography - University of Fribourg PCB : Plano-convex bottom slags Weight of PCB =quantity of work Composition of PCB =Type of work Assembly of PCBs  activity of a workshop

24. Examples of PCB assemblies from Switzerland V. Serneels, S. Perret Mineralogy and Petrography - University of Fribourg

25. Examples of PCB assemblies from Switzerland V. Serneels, S. Perret Mineralogy and Petrography - University of Fribourg

26. Vincent Serneels Sébastien Perret Mineralogy and Petrography Departement of Geoscience University of Fribourg Switzerland vincent.serneels@unifr.ch sebastien.perret@unifr.ch www.unifr.ch/mineral/archmet