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Felsites are generally light igneous or metamorphic rocks , which mainly consist of quartz and feldspar , that is, rockic minerals and have a density of less than 3 g / cm³.

The name Felsit is a case word made of feldspar (English feldspar ) and silica (English for silicon dioxide ). The corresponding adjective is felsic . Since quartz consists of silicon dioxide (SiO 2 ) - often chemically incorrectly referred to as silicic acid - the term acidic rock is often used for Felsite . However, both names are not fully synonymous , since felsic refers to the mineral stock and acidic to the chemical composition, in particular of the magma or lava from which the rock emerged. Therefore, only unmetamorphic igneous rocks are called acidic .

The adjective felsitic also stands for a fine-grained to dense structure of felsic rocks characterized by no special morphological grain formation.

Felsic glasses such as obsidian were important raw materials for tools and weapons in cultures in which metalworking was unknown.


Individual evidence

  1. Felsisch. Spectrum online encyclopedia of geosciences, accessed on August 22, 2019.