"Wood crystals"   Part 2
deutsche Version

wood in quartzAs mentioned in a previous contribution, the tissue structure of wood had apparently never been seen before preserved within quartz crystals, which is surprising as the phenomenon does not seem to be rare [1,2,3] and various other inclusions in quartz had been thoroughly investigated before [4]. There is more than one reason why the wood in quartz could have escaped notice. Inclusions of wood debris which look like dirt as in [2], Fig.12, would not arouse the attention of mineralogists. Owing to the transparency of chalcedony and quartz, silicified wood has got a dark aspect so that eventually present dark cell walls in quartz grains are easily overlooked.
Quite unexpected and largely unexplained is the appearance of the sample considered here, a small part of which, width 4.5mm, is shown here. The sample as a whole consists of silicified wood of dark aspect as seen below in the image. As an uncommon feature, the apparently dark quartz crystals had been growing into the wood, thereby more or less deforming the wood ahead of them.
What happened next is highly peculiar. Apparently some region of the wood which had not yet turned into chalcedony or quartz of dark aspect became white with a slight pink hue, for reasons unknown. (The pale pinkish white is seen on cut faces, except above left, where a cut face is darker. Free crystal faces have got a dull yellow stain.) Closer inspection reveals that the white aspect is restricted to the cell walls and possibly to a deposit on them while most of the cell lumen is clear and thus appears as a dark spot in cross-section. (See drawing below.) wood in quartz drawing

The crystal above left, partially seen with its tip, seems to have pushed the tissue aside while growing downward, then grown right through the bleached wood later, judging from the angular shape below whose angle fits to that of the dark crystal tip above.
More crystals had grown through the white wood preserving its tissue structure inside. Wood not reached by the growing crystals did not become preserved and thus vanished, leaving an empty space between the crystal tops.
The present sample is remarkable for the fact that the crystals seem to have grown effortless through the bleached wood. Comparison with other wood-in-quartz phenomena as seen in Fossil Wood News 1 is not helpful here as it only shows that the aspects differ greatly. So it appears that there will be no easy explanation for these observations. It would be of interest to know, for example, why two different crystal growth modes enclosing wood tissue could coexist in one sample. (Fig.2 in Part 1 and this image have been taken from two halves of one sample.) 

Since various wood-in-quartz phenomena have been observed repeatedly on own samples but never thoroughly investigated, they may become rewarding subjects of research.

H.-J. Weiss     2018

[1]  H.-J. Weiss: Beobachtungen an Kieselhölzern des Kyffhäuser Gebirges.
        Veröff. Mus. Naturk. Chemnitz 21(1998), 37-48.
[2]  H.-J. Weiss, R. Noll: "Holzkristalle". Veröff. Mus. Naturk. Chemnitz 22(1999), 57-64.
[3]  H. Huhle: Holz im Quarz. Veröff. Mus. Naturk. Chemnitz 27(2004), 123-24.
[4]  R. Rykart: Quarz-Monographie, Ott Verlag Thun, 1989

quartz crystal with wood inside
Fossil Wood News  30

Site map
Fossil Wood News
Silicified wood