Currently refers to igneous rock that contains more than 60 % of silica by weight. Originally the term 'acid rock' was based on the archaic concept that rocks high in silicon contained silicic acid, and thus could be considered acidic. Although that is known not to be the case, the term is still used for silicon-rich rock. Typical acid rock is light colored with a low specific gravity. An example of an acid rock is rhyolite. The weathered surface of acid rock can become very white due to the degradation of orthoclase.
Synonyms and Related Terms
acidic rock; rocha ácida (Port.)
Sources Checked for Data in Record
- Submitted information Comment: José Delgado Rodrigues, LNEC, 2009.