BGS Rock Classification Scheme
Ultramafic-rock - A type of coarse-grained normal crystalline rock. In the Rock Classification Scheme, a rock is ultramafic if the proportion of mafic minerals (M) is greater than 90%. They are classified according to their mafic mineral content, namely olivine, orthopyroxene, clinopyroxene and hornblende. The class includes peridotite, pyroxenite, and hornblendite. The term may be used as a field classification when an accurate mineral mode from thin section examination is not available. British Geological Survey Research Report RR/99/06, section 5.1 and figs. 9, 12.
| Code | UMR |
|---|---|
| Description | Ultramafic-rock - A type of coarse-grained normal crystalline rock. In the Rock Classification Scheme, a rock is ultramafic if the proportion of mafic minerals (M) is greater than 90%. They are classified according to their mafic mineral content, namely olivine, orthopyroxene, clinopyroxene and hornblende. The class includes peridotite, pyroxenite, and hornblendite. The term may be used as a field classification when an accurate mineral mode from thin section examination is not available. British Geological Survey Research Report RR/99/06, section 5.1 and figs. 9, 12. |
| Qualifiers | No qualifiers currently exist. |
| Definition | Not Available |
| Linked data | http://data.bgs.ac.uk/id/EarthMaterialClass/RockName/UMR |
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.