Magnesite - Veitsch, Styria


     
Description: Coarse grained, sparry magnesite (light brown) is partly replacing grey, Carboniferous dolomite, rich in biogene detritus.
A: Magnesite partly replacing a crinoid fragment.
B: Redolomitisation of magnesite in the vicinity of dolomite-filled veinlet.
C: Enrichment of the clay minerals and organic matter of the dolomite at the edges and between replacing magnesite crystals.
Genesis: Partial metasomatic replacement of Carboniferous dolomite by magnesite. But the genesis remains controversal, especially the time
of magnesite formation. It could be either: very early diagenetic(?); late diagenetic; due to a hydrothermal event in the Permo-Triassic;
during Eo-Alpine metmorphism. One of the problem is the undoubted Eo-Alpine greenschist facies overprint of the magnesite-bearing series,
possibly resulting in recrystallization, redistribution of magnesite (thereby causing epigenetic features like above!?) and the obliteration of
pre-Eo-Alpine textures.
Time of magnesite formation: Possibly Permo-Triassic.
Locality: Abandoned magnesite mine Sattlerkogel, Veitsch, Styria, Austria.
References: Prochaska, 2001
Sample details: Collected November 2002. Polished slab. Field of view 14 cm. Sample AN152.
last changes: 6.10.2003.