An uncommon chert sample with Rhynia
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uncommon Rhynie chert sample
Fossiliferous chert samples are usually found as fragments of chert layers with crack faces from brittle fracture on their surface, which often reveal part of the fossil content by inspection from outside. The quite uncommon small sample of Rhynie chert in Fig.1, without the large fracture faces often seen on chert samples, must have been torn off at an early stage while the hardening stratum was still gel-like, with plant parts already more solid, now partially sticking out (Fig.2) and making a bumpy surface.
Some small brittle cracks had been formed later after the silica gel had turned into hard chalcedony (Fig.3).

Fig.1: Uncommon sample of Rhynie chert: rugged boundary and bumpy surface with abundant broken Rhynia; remains of sandstone in pockets. Width of the picture 7.5cm.

Fig.2 (below): Detail from the bumpy surface: Rhynia with epidermis, broken off. Width of the picture 5mm.

Rhynia on the sample surfaceRhynia sections

Fig.3 (right): Rhynia in various stages of deformation and damage; small-scale brittle fracture below.
Width of the picture 8mm.

Fig.4 (below left, detail of Fig.3): Rhynia, enigmatic type of damage.
Width of the picture 2.5mm.
Rhynia damagedfungus

Fig.5 (left, detail of Fig.3): Rhynia, deformed, with enigmatic organism inside and outside.

Width of the picture 1mm. See also Rhynie Chert News 165.

Samples without the typical aspect of fossiliferous chert, without larger fracture faces and with a bumpy surface, may be easily overlooked. Like any other Rhynie chert sample they are worth being inspected since they might reveal a surprise, as the one in Fig.5.
Sample: Rh22/4 (70g), found at Castlehill near Rhynie in 2009.

H.-J. Weiss       2020
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