Fossil wood aspects
deutsche Version
Fossil wood fragments are so abundant at some places that samples of average quality would not arouse attention. Nevertheless, experience has shown that occasionally a sample is found which deserves closer inspection (as, for example, the ones described in Fossil Wood News 1, 15, 19,  21, 28, 30, 32, 33, 36, 38, 40). 
wood tissue
Fig.1: Permian coniferous wood cross-section, cells with different fills. Image width 2mm.

Sample Kc/14 found by Andrea Weiss at Kleincarsdorf on 26.12.1997;

The cross-section seen here, most probably of Permian coniferous wood, obviously had undergone differing silicification processes. Judging from the shadows, the cells below left look as if they were empty but are filled with clear chalcedony. The blue-milk stain of the majority of cells arose when the crystal grain size in the chalcedony reached the wavelength of light. The black stain in some of the cells may be due to black clots consisting of fungus hyphae (as in Fossil Wood News 4).

Fig.2 (below): Permian stem cross-section with peculiar boundary between central pith and onset of wood: large pith cells above, wood cells in radial rows extending downwards. Image width 1.3mm.
Sample Kc/24 found at Kleincarsdorf, Doehlen basin, in the nineties.
Note that the pith cells (above right in Fig.2) are huge compared to the wood cells below.
The white stain of part of the cells seems to be due to crystal grain growth in clear chalcedony (as in Fig.1) but probably triggered by microbial activity here.
The walls of the wood cells are mostly seen as pale but some of them appear as black. Closer inspection shows that there may be a black coating, of probably microbial origin, on the inside of the wall while the outside of the wall, belonging to a neighbouring cell, is still pale.
As distinctly seen with two separate dark cells near the middle of this picture, the interior of the cells with coated walls is darker since the incident light does not enter. A few cells nearby show quite the opposite: black walls but white fills. This is peculiar but not contradictory, of course.
Black coatings on cell walls are common phenomena with early land plants, as mentioned in Rhynie Chert News 83 and 172.

H.-J. Weiss   2023

quartz crystal with wood inside
Fossil Wood News  44
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