Silicate rock

Silicate rocks are the most common rocks in the earth's crust . They mainly consist of silicate minerals such as feldspars , quartz , amphiboles , pyroxenes or foids . The contrast to silicate rocks are carbonate rocks .

While in petrography, as a sub-area of ​​research-oriented geology, instead of silicate rocks , they speak of their constituents, the silicate minerals , and the rough classification of the rocks is not based on their composition, but rather on their formation, the term silicate rocks is used in engineering geology and in the Construction technology relatively familiar. Construction practice also speaks - albeit not entirely correctly - of "hard stones".

In fact, most of the rocks designated as silicate rocks are either igneous or deep rocks or metamorphic rocks (of various origins) in the petrographic sense, while carbonate rocks are primarily understood as sedimentary rocks (especially limestones ). The bright constituents of typical silicate rocks include quartz, feldspars and foids, which are also known as felsic minerals . Dark or mafic components of silicate rocks are mainly pyroxenes , amphiboles and biotite - mica .

The naming of individual silicate rock types is based on the general petrographic nomenclature, i.e. mostly on the proportion of the minerals involved (in igneous rocks an expression of the chemistry of the initial melt , in metamorphic rocks also an expression of the formation conditions ) as well as structural features (e.g. foliation and prevailing grain size , again depending on the formation conditions).

literature

• Alan R. Woolley, A. Clive Bishop, W. Roger Hamilton: The Cosmos Stone Guide. Minerals, rocks, fossils . 4th edition. Franckh-Kosmos Verlag, Stuttgart 1980, ISBN 978-3-440-04718-7 , p. 146 ff. (Section rocks )