Black fossil wood bleached
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Well preserved silicified wood with black aspect has repeatedly been mistaken for fossil charcoal [1, 2, 3]. Since real fossil charcoal is of scientific interest in palaeobotany [4], the subject is worth being considered once more. One particular sample, found in the Lower Permian Döhlen Basin in 1992 and declared fossil charcoal by professionals, has provided several details contradicting the charcoal interpretation, as explained in Fossil Wood News 9,
3537, 38, 40.
black wood bleachedPolished faces of petrified wood may appear dark or nearly black. A closer look shows that the dark aspect may be due to dark or transparent fills within the cells. Less often the cell walls are distinctly black, as in Fig.1 above the gap.

Large deformations of tissue as in Fig.2 and Fossil Wood News 40 are not compatible with charcoal. Pale spots in black tissue seem to indicate wood rather than charcoal. black wood deformed and bleached

Fig.1 (right): Black wood torn asunder while soft, silicified; progress of bleaching from below stopped at gap. Image width 2mm.

Fig.2 (left): Black wood deformed while soft, silicified, locally bleached; same sample. Image width 1mm.

Below the gap in Fig.1 the tissue is slightly less black, with brown pith rays in between, hence some bleaching process proceeding from below had ended at the gap. Probably the tissue was black throughout but became pale brown locally, with depth of bleaching up to 10mm: Fig.2. These images and previous contributions suggest a sequence of events as
This sample does not serve as evidence of 
a burning tree crushing into the swamp, as recently proposed [3]. It is rather a fragment of a tree trunk which had lain in the swamp for some time, turned black there, was locally deformed and torn into pieces of various size while still soft, got silicified into hard chalcedony (chert) together with the swamp water filling wood cells and gaps, then broke into parts which, lying in some Lower Permian sediment for an indefinite time, became superficially bleached, eventually came out when the strata of the Döhlen Basin were partially eroded, and finally ended up in the top soil at Wilmsdorf, together with "common" fossil wood and less common fossil tree ferns.
Sample: W/55, found in 1992 at Wilmsdorf, Döhlen Basin near Dresden, Saxony.
A question is left: What are the black stains on the cell walls, if not carbon from charcoal ? Possibly they are microbial coatings turned black after the decay of the microbes, like those occasionally seen on other fossil plants and fungi (Rhynie Chert News 83, 85, 104, 181), .

H.-J. Weiss   2022

[1]  R. Rössler: Der versteinerte Wald von Chemnitz. Museum f. Naturkunde Chemnitz, 2001, 179.
[2]  R. Noll, V. Wilde :  Conifers from the „Uplands“ – Petrified wood from Central Germany, 
       in: U. Dernbach, W.D. Tidwell : Secrets of Petrified Plants, D'ORO Publ., 2002, 88-103.
[3]  R. Rössler, Habilitation lecture, Freiberg.
[4]  A. Jasper, A. Pozzebon-Silva, J. Carniere, D. Uhl : Palaeozoic and Mesozoic palaeo-wildfires: An overview on advances ... ( 2021) 

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