Peculiar structures
deutsche Version
This section of Chert News is a random compilation of conspicuous structures and patterns, mainly in cherts and other silicites, worth looking at and marvelling about since they provide insights into structure formation, silicification, and fossilisation, or they concern some palaeontological detail. Also they may pose a problem to be solved.
Own samples: Lower Devonian and Uppermost Carboniferous /Lower Permian if not indicated otherwise.
All pictures of own samples have been taken with incident light. Adopted from the literature: 7, 17, 23, 34.
The order of the below images is random and unrelated to the order and numbering of the descriptions on separate pages.

Clicking on the picture leads to a more or less detailed description of the subject, with or without explanation, on a separate
Chert News page,
        ( not yet available for image Nr. 2, 4, 13, 30, 33, 36. )
A one-line explanatory description of every picture is given at the bottom of this page.

early shrinkage cracks in peat coated needle-like crystals resembling plant fragments wood inside quartz grown in degraded woodenigmatic structures in agate-like chalcedony pyrite shapes surrounded by decay products

wood torn asunder before silicificationdegraded wood, shrunk and broken during silicificationRhynia shrunk after silica gel formation in the waterconiferous-type wood with structured spots formed during silicificationAglaophyton epidermis pattern

incidental aggregation of unrelated objectsclots in wood usually misinterpreted as coproliteschalcedony bulges resembling permian tree fern pinnulescentral Pachytheca well silicified in Rhynie chertshrinkage cracks of rare aspect in wood

hollow calamite branch partconiferous wood mistaken for tree fern stemaligned nematophyte tubes in cross-sectionuncommon aspect of Aglaophyton epidermisAsteroxylon central strand, bleached

Trichopherophyton central strandconiferous wood, inclined sections of tracheids and pith raysCosmochlaina cuticle, no cellsshrinkage cracks in silicified peattree fern sporangia tips, hairy species

tangle of nematophyte tubescalamite wood with wide pith raysPsaronius aerial roots filled with agatescyanobacteria sheets stained with iron oxideswalnut branch pith (recent) resembling cordaite pith

tiny calamite with small wood ring and cortexshrinkage crack castspherulite of uncommon aspect among cells
wood inside quartz crystals

borings in Jurassic rock, Kimmeridge
fungus effects in AglaophytonVentarura ring tissue   straight hypha, coated

Concise comments on the images

1: shrinkage cracks in peat, formed in an early stage of silicification
2: needle-like crystals coated with dark deposit, thus resembling Devonian plant fragments
3: quartz crystals grown in soft degraded wood, with inclusions of wood or debris
4: enigmatic structures in agate-like chalcedony
5: gypsum crystals stained with iron oxides, grown from dissolving pyrite cubes in Permian chert
6: coniferous-type wood, pith rays torn asunder before silicification
7: degraded wood, shrunk and broken into blocks in an early stage of silicification
8: Rhynia shrunk after the surrounding water had turned into silica gel
9: coniferous-type wood with structured spots formed in an early stage of silicification
Aglaophyton epidermis pattern, exceptionally well seen as a dainty meshwork
11: cracks, white precipitate, coated fungus hypha ("eye")
arranged incidentally, Rhynie chert
12: clots in silicified wood usually misinterpreted as mite coprolites, Lower Permian
13: bulging shapes
resembling Permian tree fern pinnules on the surface of a chalcedony nodule 
14: central cut face of well silicified Pachytheca in Rhynie chert
15: tunnel-like cracks with rhombic cross-section in wood, formed in an early stage of silicification
16: hollow calamite branch providing an illusion depending on illumination
17: coniferous wood patterned in silicification, easily mistaken for tree fern stem section
18: bunch of aligned nematophyte tubes in cross-section, Rhynie chert
19: Aglaophyton epidermis pattern
with stark contrast due to an enigmatic dark deposit in every cell
20: Asteroxylon central strand and "leaf-trace" cross-sections, bleached (by oxidation during silicification?)
21: Trichopherophyton central strand fragments, incidentally cut across and lengthwise
22: coniferous wood, slightly inclined sections of tracheids and pith rays
23: Cosmochlaina cuticle (Silurian), usually misinterpreted as an enigmatic cell structure
24: 3-D shrinkage crack pattern in silicified peat
25: tree fern sporangia tips, uncommon hairy variety or species
26: tangle of nematophyte tubes in Rhynie chert
27: calamite wood, tangential section with uncommonly wide pith rays in cross-section
28: Psaronius, hollow aerial root cross-sections filled with agates
29: cyanobacteria sheets stained with iron oxides in Permian chert
30: walnut branch pith (recent) resembling the Artisia pith of the palaeozoic cordaites 
31: tiny calamite with hollow center, small wood ring, and cortex
32: shrinkage crack casts in poorly preserved petrified wood
33: spherulite of uncommon aspect in plant tissue in Rhynie chert
34: alleged coprolites in the xylem but really fungus clots in the phloem of a Psaronius aerial root
35: wood tissue preserved inside quartz crystals, Kyffhäuser mountains
36: borings in limestone resembling Meandropolydora except for loops within one another; Kimmeridge
37: fungus-induced small dots and big holes in Aglaophyton
38: part of the enigmatic persistent cortex ring usually seen on Ventarura cross-sections
39: fungus hyphae grown in water-filled cavity, coated with chalzedony and quartz topping

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