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Microscopy and Microanalysis of Magmatic and Metamorphic Minerals – Part 1: Cordierite

Published online by Cambridge University Press:  14 March 2018

Robert Sturm
Robert Sturm*
Affiliation:
Brunnleitenweg 41, A-5061 Elsbethen, Salzburg/Austria
*
Robert.Sturm@sbg.ac.at

Extract

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Cordierite represents an orthorhombic (Mg,Fe)Al-silicate (Table 1) that is observed in a wide range of natural occurrences. As outlined in numerous mineralogical overviews published during the past decades, cordierite mainly crystallizes in thermally metamorphosed rocks, particularly in those derived from argillaceous sediments. Additionally, the mineral can be a major constituent of parageneses formed under high-grade regional metamorphism and therefore occurs in respective schists, gneisses and granulites. The metamorphic formation of cordierite is generally restricted to conditions of deficient or low shearing stress producing only moderate lithological pressures. With rising pressure due to transpression cordierite often breaks down to enstatite and sillimanite or, at higher temperature, to sapphirine and quartz (see also Fig. 5). Besides its crystallization in metamorphic rocks, cordierite is also found in specific igneous rocks like peraluminous granites and related high-grade anatectic terrains.

Type
Research Article
Information
Microscopy Today , Volume 16 , Issue 5 , September 2008 , pp. 30 - 37
Copyright
Copyright © Microscopy Society of America 2008

References

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