BGS Rock Classification Scheme
Trachytic-rock - A type of felsite. In the Rock Classification Scheme, this class includes trachyte, latite and similar rocks. The term may be used as a field classification when an accurate mineral mode from thin section examination, or a chemical analysis, is not available. British Geological Survey Research Report RR/99/06, section 5.2 and figs. 17, 18.
| Code | TRR |
|---|---|
| Description | Trachytic-rock - A type of felsite. In the Rock Classification Scheme, this class includes trachyte, latite and similar rocks. The term may be used as a field classification when an accurate mineral mode from thin section examination, or a chemical analysis, is not available. British Geological Survey Research Report RR/99/06, section 5.2 and figs. 17, 18. |
| Qualifiers | No qualifiers currently exist. |
| Definition | Fine-grained, av. <0.25mm normal crystalline extrusive/intrusive rock; quartz <20% or felspathoid <10% of QAPF, feldspar >35% alkali feldspar, TAS SiO2 57.6-69wt%, Na2O+K2O >7wt%; normative quartz <20% |
| Linked data | http://data.bgs.ac.uk/id/EarthMaterialClass/RockName/TRR |
CAVEAT
"Thumbnail" definitions attached to some of the table entries are an interim attempt to provide simple short descriptions of the "unqualified" rock types presented within the BGS Rock Classification Scheme. Every effort has been made to ensure accuracy and consistency but minor contradictions or omissions might be present. The BGS welcomes any feedback pointing out such minor imperfections and/or providing constructive comment and suggestions for improvement of the definitions. In the first instance such feedback should be directed to Dr Tim McCormick.