Dear Marcello and others,
Bruce Yardley's definition is as precise as any you'll find, I suspect.
The Glossary of Geology gives "calc-silicate rock" as a metamorphic rock
consisting mainly of Ca-bearing silicates (di, wo) formed by
metamorphism of impure limestone or dolomite. Your rock fits this
definition.
The Glossary also gives the term "calc-silicate marble" for a marble in
which Ca(-Mg) silicates are conspicuous. Common sense might suggest
using about 50% carbonate minerals as a boundary between these rock
names.
The term skarn, on the other hand, is a more dangerous one, as it tends
to imply an association with some or all of contact metamorphism,
hydrothermal Fe and/or sulphide ore deposits, and metasomatic mass
transfer (typically of Fe, Al and Si).
Dave
Marcello Franceschelli wrote:
>
> Dear all,
>
> Yardley in the book "An Introduction to Metamorphic Petrology"
> pag. 126 writes.........
> ....it becomes convenient for the description of metamorphosed
> calcareous sediments
> to divide them into two categories: marbles in which carbonates are
> abundant; and calc-silicates
> with little or no carbonate.
> Can anyone suggest me if a rock made up of calcite ( 30%) , and
> wollastonite+diopside+
> grossular+ quartz (70%) can be classified as calc-silicate?
> Thanks in advance,
> Marcello Franceschelli
>
> _________________________________________
>
> Prof. Marcello Franceschelli
>
> Dipartimento di Scienze della Terra
> Università degli Studi di Cagliari
> Via Trentino, 51
> I-09127 Cagliari
> Italy
>
> [log in to unmask]
> Tel: +39 -070 6757713 Fax: +39 -070 282236
> ____________________________________
--
Dave Waters - Lecturer in Metamorphic Petrology, Oxford University
Dept of Earth Sciences, Parks Rd, Oxford OX1 3PR, UK
Tel: +44 1865 272000
Direct: +44 1865 272058 Email: [log in to unmask]
Fax: +44 1865 272072 http://www.earth.ox.ac.uk/~davewa/
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