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RISE PROJECT: MÜNSTER PHILOSOPHICUM
Emilie Lozier1, Ferdinand Drünert1, Doris Möncke1, Lothar Wondraczek1 1 Otto-Schott-Institute of Materials Research, Friedrich-Schiller-University Jena, Germany
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Introduction Hundreds of shards of corroded soda-lime-silicate glass
Discovered by Peter Steppuhn From the Münster Philisophicum We received 70+ Samples date to 13th-14th century CE One set of samples is about 200 years younger Dating is relative, likely based on stratigraphic evidence Our Goals Classify glass types Compositionally distinguish the younger glasses from the older ones Draw conclusions as to the types of resources that were used
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Methods UV-vis spectrophotometry X-ray fluorescence (XRF)
CARY instrument at OSI Measured absorption X-ray fluorescence (XRF) Museum für Ur- und Frühgeschichte Thüringens Took 3 measurements, averaged wt% values for 21 elements IR microscopy Instrument at OSI Measured reflected light
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Sample Preparation 13 samples were broken and polished
Destructive methods authorized by Steppuhn Polishing improved UV-vis spectra quality Increased accuracy of XRF measurements Na2O MgO Al2O3 SiO2 P2O5 K2O CaO TiO2 MnO Fe2O3 ZnO Average 0.86 2.7 2.3 54 2.4 11 21 0.23 1.0 0.72 0.04 Corrosion 2.0 0.46 3.8 62 1.9 0.56 6.0 17 1.6 0.21
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Sample Divisions Red glass Brown glass Yellow glass Pale green glass, 3 types Dark green glass Blue glass, 2 types
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Red Brown Yellow Pale Green Type 1 Pale Green Type 2 Pale Green Type 3 Dark Green Blue Type 1 Blue Type 2
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Sample Divisions Red glass Brown glass Yellow glass Pale green glass, 3 types Dark green glass Blue glass, 2 types
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Red Glass Description Pale green base glass Flashed red layer
030-1 Description Pale green base glass Flashed red layer Brown corrosion Includes sample sets 030, 031 Compositionally distinct from other sets
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Sample Divisions Red glass Brown glass Yellow glass Pale green glass, 3 types Dark green glass Blue glass, 2 types
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Brown Glass Description Brown base glass Brown corrosion
213-7 Description Brown base glass Brown corrosion Some surface painting Includes 213-3, 213-7, , , , 220-4
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Sample Divisions Red glass Brown glass Yellow glass Pale green glass, 3 types Dark green glass Blue glass, 2 types
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Yellow Glass Description Dark yellow glass
213-11 Description Dark yellow glass Varying levels of brown corrosion Includes 213-2, 213-5, ,
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Sample Divisions Red glass Brown glass Yellow glass Pale green glass, 3 types Dark green glass Blue glass, 2 types
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Pale Green Glass Type 1 Description Pale green glass Brown corrosion
213-11 Description Pale green glass Brown corrosion Includes 213-1, 213-4, 213-6, 213-9
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Pale Green Glass Type 2 Description Pale green to pale blue glass
220-3 Description Pale green to pale blue glass Varying levels of brown corrosion Includes sample sets 220 (excluding 220-4), 222, 223
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Pale Green Glass Type 3 Description Pale green glass
Brown to iridescent corrosion 200 years younger Includes sample set 174 Compositionally distinct from other sample sets by K2O/BaO ratio, Wedepohl et al [2010]
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Sample Divisions Red glass Brown glass Yellow glass Pale green glass, 3 types Dark green glass Blue glass, 2 types
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Dark Green Glass Description Dark green glass Minimal corrosion
064-1 Dark Green Glass Description Dark green glass Minimal corrosion Partial surface painting Includes sample sets 064, 067 XRF indicates presence of lead
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Sample Divisions Red glass Brown glass Yellow glass Pale green glass, 3 types Dark green glass Blue glass, 2 types
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Blue Glass Types 1, 2 Description Deep blue glass
037-2 Blue Glass Types 1, 2 Description Deep blue glass Minimal corrosion (Type 1) Gray corrosion layer (Type 2) Type 1 – sample set 037 Type 2 – sample set 216 Cobalt peaks for Type 2 are shifted left 216-5
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Summary Data allows us to group samples
Excluding younger glasses (174) Excluding flashed red glasses (030, 031) and lead-containing glasses (064, 067) Main body of samples may have used beech ash CaO/K2O ratio for samples is ~2 CaO/K2O ratio for beech trunks is 1 to 2, Wedepohl et al [2010] CaO/MgO ratio is too high for beech, but lime may have been added to melt Impure silica source (river sand?) was likely used Alumina content of samples is >1%, Verita et al [2013]
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Outlook Determine concentrations of coloring agents
Estimate standard deviation of XRF data Use LA-ICP-MS to evaluate trace elements Lower LOD than XRF or UV-vis Could help determine providence of resources Calculate Fe2+/Fe3+ ratio Evaluate collected IR data
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Bibliography Verita, M. et al Compositional analysis of 14th-15th century enamels from the altar of San Giovanni in Florence: An Integrated study by portable X-ray fluorescence and electron probe microanalysis. Archaeom; 55(6): Wedepohl, H.K. et al The chemical composition of medieval wood ash glass from Central Europe. Chemie der Erde; 70:89-97
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Thank you very much for your attention!
Contact Otto-Schott Institute of Materials Research Fraunhoferstr. 6 07743 Jena
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