Mössbauer studies of subfossil oak

Abstract

Subfossil oak wood found in a dried-up bog in Bavaria, Germany, was studied by Mössbauer spectroscopy. The bog oaks contain substantial amounts of iron taken up from the bog waters and presumably forming complexes with the tanning agents in the oak wood. The iron is mainly Fe 3+ and much of this exhibits an uncommonly large quadrupole splitting of up to 1.6 mm/s that can tentatively be explained by the formation of oxo-bridged iron dimers. Only rarely, mainly in the dense wood of the roots of bog oaks, was divalent iron found. When the wood was ground to a powder the divalent iron oxidized to Fe 3+ within hours. This suggests that iron is taken up from the bog water as Fe 2+ and oxidizes only when the wood emerges from the water and comes into contact with air.

Mössbauer Spectroscopic Characterization of Iron in Ashes Made from the Ancient Woods Excavated in the Foothills of Mt. Chokai

“…[2][3][4][5][6] Fe is enriched, to varying degrees, in umoregi wood, 6 but no studies are available on the chemical state of Fe in umoregi wood except for two reports using 57 Fe-Mössbauer spectroscopy. 7,8 In addition, there is little scientific information about the ash made from umoregi wood.…”

Influence of Ageing on Abrasion Volume Loss, Density, and Structural Components of Subfossil Oak

“…We selected the test specimens from oak trunks with an as similar as possible growth ring width (1.3-1.9 mm),to avoid the influence of the percentage of late and early wood on abrasion wear resistance [30]. The samples of subfossil oak were much darker than the sample of recent oak (Figure 2), owing to the reaction between the iron from the riverbed soil and the tannins in the oak wood [7]. Microstructure analysis, abrasion wear resistance testing, density measurements, moisture content measurements, and FTIR analysis were performed on all samples, from 0 to 6.…”

“…Due to mineral deposition from river water into the wood, the durability, appearance, and structure of the wood are modified [4][5][6]. Subfossil oak is highly appreciated for its hardness and durability as well for its attractive dark color and good acoustic properties and is therefore often used for the production of musical instruments, ornaments, jewelry, sculptures, and also for luxurious furniture, parquet, and veneers [2,7,8].…”

“…However, these changes caused by time as well as the conclusions reached by different examiners have not always been consistent. The reason for that is the different aquatic conditions in which the examined samples originated [7,[20][21][22][23][24].…”

Mössbauer Characterization of Iron in Ancient Buried Trees Excavated from the Foothills of Mt. Chokai

“…From studies of iron-gall ink [6][7][8][9][10] and dark spots on timber due to Fe contamination, [11][12][13] it has been recognized that the characteristic color of umoregi wood arises from reactions between Fe and polyphenols such as tannin. Only two studies 14,15 on Fe in umoregi wood have been reported so far, and they made no mention of the coloring mechanism, although they investigated the chemical states of Fe in the wood using Mössbauer spectroscopy.…”