Gold Mine Wooden Artefacts: Multianalytical Investigations for the Selection of Appropriate Consolidation Treatments

Abstract

Environmental conditions present in mines generally are very favourable to decay; high temperature, high humidity, variable oxygen content, numerous metal-wood connections and the presence of a high content of inorganic compounds typical of mines have a significant impact on the biotic and abiotic degradation factors. The state of conservation of wooden artefacts from the Złoty Stok (Poland) gold mine was investigated using a multi-analytical approach. The aim was to select the conservation treatments that would stop decay and improve the conditions and dimensional stability of the wood. FT-IR and Py-GC/MS were used to assess the state of preservation of lignocellulosic material. ED-XRF and SEM-EDS were used to determine-and XRD to identify crystalline phases-salts and minerals in the wood structure or efflorescence on the surface. Highly degraded lignocellulosic material that had undergone depolymerisation and oxidation was found to be severely contaminated by iron-based mineral substances, mainly pyrite, and in some cases greigite and magnetite. The presence of inorganic salts made it difficult to choose the best consolidating material to reduce the level of decay and improve the dimensional stability of the wood.

Keywords: ED-XRF; FT-IR; Py-GC/MS; SEM-EDS; minerals; waterlogged wood.

Figure 1

FTIR spectra of archaeological pine wood samples and reference pine wood sample.

Figure 2

FTIR spectra of archaeological spruce wood samples and reference spruce wood sample.

Figure 3

Py-GC-MS chromatographic profiles obtained for archaeological wood sample (a) S2 (spruce) and (b) P2 (pine). Numbers refer to Table 5.

Figure 4

Distribution of (a) holocellulose and (b) lignin pyrolysis products from sound pine (Reference pine) and spruce (Reference spruce) wood samples, and archaeological pine (P1, P2 and P3) and spruce (S1 and S2) wood specimens. Relative abundances are expressed as percentages relative to total holocellulose (a) and total lignin fractions (b), respectively.

Figure 5

Selected ED-XRF spectra of archaeological wood samples S1 (a), P1 (b), S2 (c) and P2 (d) and reference wood samples (control) for P1 and P2 pine reference wood and for S1 and S2 spruce reference wood.

Figure 6

SEM images and EDS spectra for selected archaeological samples: S2 (a), P1 (b,c) and P3 (d).

Figure 7

X-ray patterns of samples S1 and P3 with related spruce and pine references (in blue lines diffraction peaks of pyrite, in green greigite, in gray magnetite).

Figure 8

Wooden elements from a paternoster pump, where (a) ladder and the mine drainage system: (b,c) pipes, and (d) trough.