BGS Rock Classification Scheme
Ortho-amphibolite - A type of metamafic-rock. In the Rock Classification Scheme, it is one composed largely of hornblende and feldspar. This mineralogy reflects amphibolite facies conditions. Note the ortho- prefix indicates a rock that is thought to have an igneous protolith, in contrast with para-amphibolite which has a sedimentary protolith, and amphibolite where the nature of the protolith is not defined. British Geological Survey Research Report RR/99/02, section 5.2.
| Code | OAMPHB |
|---|---|
| Description | Ortho-amphibolite - A type of metamafic-rock. In the Rock Classification Scheme, it is one composed largely of hornblende and feldspar. This mineralogy reflects amphibolite facies conditions. Note the ortho- prefix indicates a rock that is thought to have an igneous protolith, in contrast with para-amphibolite which has a sedimentary protolith, and amphibolite where the nature of the protolith is not defined. British Geological Survey Research Report RR/99/02, section 5.2. |
| Qualifiers | No qualifiers currently exist. |
| Definition | Crystalloblastic, commonly foliated meta-igneous rock (grain size & protolith undefined); 35-90% mafic minerals, hornblende+plagioclase dominant +/-garnet/biotite/quartz |
| Linked data | http://data.bgs.ac.uk/id/EarthMaterialClass/RockName/OAMPHB |
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.