Red chert --- offering fossils and fancy artwork
deutsche Version

red chert from Weak LawFossils embedded in chert may be preserved with tiny details but only a few of the large variety of chert types offer fossils at all. Famous among palaeontologists is the Rhynie chert since its fossils represent an early habitat dating back to times when the plants began to emerge from pools and swamps and to occupy dry land.
Some pools and swamps
with things grown there or fallen in became silicified by water rich in silica from leached volcanic "ashes". Part of these cherts may be distinguished by red and yellow stains due to fine-disperse iron oxides. Hence, red cherts are worth being closely inspected in order to find out whether they are mere accumulations of red mineral grains or stained silicified swamp matter with prospective fossil content.
In this context, large amounts of red cherts from the Döhlen basin (Lower Permian) have been inspected and partially commented on:
Permian Chert News  8, 14, 17, 18, 25, 27, 28, 36, 37, 38, 39.

As a by-product of such activity, the only sample of red chert found on the beach at Weak Law has provided surprising structures combined with problems to be solved.

Fig.1: Apparition in red chert found on the beach at Weak Law near Gullane, Scotland. 
Image width 4.3mm.
Fig.2: "Sponge-like" yellow spot in red chert, detail of Fig.1.  Image width 1.4mm. 

From the aspect of the red floccules in clear chalcedony (Fig.1) it may be concluded that they had formed a suspension or loose arrangement with clear water in between. The apparent randomness of the floccules seems to indicate that there are no plant or animal structures involved. Clearly more uniform is the yellow area, structured like a rubber sponge.
As a trivial fact, the crack in Fig.2 had formed when the substance was no more fluid. Hence the red stain along the crack, and possibly all other red stains, had formed when
the substance was gel-like or solid. The question arises whether or not this could be compatible with the assumption that the floccules were aggregates of cyanobacteria whose oxygen production caused the formation and deposition of hematite.      

There seems to be no simple explanation for the funny face in Fig.1. The "eyeball" on the left seems to have been cleared from hematite by total bleaching of a space with a well-defined boundary, not quite so on the right. The thin plates in the "eyes", tilted towards the cut and polished sample face, indicate some fluid level during silicification. The inclined sections of the plates appear as narrow white lines, with the remaining part of the plates extending into the depth.
The chert sample of 10cm width and 5cm height, 0.53kg, had been a fragment of a chert layer or lens, become slightly rounded, then embedded into non-chert sediment
. Eventually the sediment rock decayed and the chert came out on the beach, with a gray 2cm-lump consisting of two types of sediment still sticking to the outside.
It cannot be excluded, of course, that the pebble is not related to Weak Law where it was found but had come along the beach from some other place. It has tentatively been placed here among Permian cherts. Anyway, the uncanny face may serve as a reminder that red cherts deserve a closer look as they may offer something interesting.
H.-J. Weiss      2022
Scolecopteris pinnule cross-section, Sardinia Permian Chert News40
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