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Quartz Var Eisenkiesel Psm Fossil Stromatolites

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Quartz Var Eisenkiesel Psm Fossil Stromatolites

Pseudomorph

Description Tabs

Description
Locality: 
Rösenbeck Quarries, Brilon, Arnsberg, North Rhine - Westphalia, Germany
Size Range: 
Small cabinet (7-10 cm)
Size: 
9.3 × 7 × 2.5 cm
Description

A very beautiful cut and polished slice of fossil stromatolites replaced by iron-oxides and quartz. This comes from the same geological structure as the fossil fungi mycelium, basically the breeding ground for those fungi. Up to date the only localities worldwide for this material are in the Sauerland area - "type locality" Warstein. Here's an extract from a German publication: Fossil fungi in iron stromatolites from Warstein (Rhenish Massif, Northwestern Germany) Zeitschrift Facies Verlag Springer Berlin / Heidelberg ISSN 0172-9179 (Print) 1612-4820 (Online) Heft Volume 7, Number 1 / Dezember 1982 DOI 10.1007/BF02537228 Seiten 237-259 Fachgebiete Geo- und Umweltwissenschaften. Fossil iron stromatolites, formed by fungi, have been found near Warstein, W. Germany. The stromatolitic and massive ferruginous quartzes are always confined to karstic hollow molds of the Devonian "Massenkalk". The few autochthonous occurrences show that these are chalcedony-quartz-silicifations of mainly ac-oriented, corrosively widened cracks. The fungal filaments are generally encrusted with goethite and appear in stromatolitic, massive and patch-like forms. The fungi can be referred to the order Mucorales and the genera Chaetomium, Preussia, and Papulaspora. An Oligocene/Miocene age is presumed according to the development of the karst, the mineral paragenesis, and microthermometrical measurements. The fungal mycelia grew on cracks and other hollow molds of the Devonian "Massenkalk" (massive reef limestones) in the vadose zone. Percolating water transported organic C originating from the soil-/sedimentary cover as a substratum for the fungi as well as chelated and free Fe2+ and colloidal Fe3+. Iron was precipitated on the cell walls of the fungal filaments, and thus further precipitation was initiated. Iron-rich layers formed. Gradual dehydration finally led to the formation of goethite. Gel splits and settling structures have often been observed in these regions. The silicification starting within this phase conserved the partially rather fragile structures. The iron stromatolites of Warstein are probably the first examples of fossil biogenic, non-photosynthetic laminites.
I've recently heard about new publications which attribute the organic stromatolitic structures to fossil bacteria.
On the backside you can see eisenkiesel crystals with inclusions of those or the before-mentioned fungi mycelia.

Mineral Data
What's on the rock

Quartz

Formula: 
SiO2
Strunz: 
4.DA.05
Crystal System: 
Trigonal
Hardness: 
7.0
Streak: 
White

Eisenkiesel

Variety Of: 

Quartz

Formula: 
SiO2
Strunz: 
4.DA.05
Hardness: 
7.0

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