BGS Rock Classification Scheme - Text search results
220 records found. Please click on a code for a "thumbnail" definition.
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| Description | Code |
|---|---|
| Basaltic lava, olivine-basalt and angular pebble-grade conglomerate | BLOBCP |
| Basaltic lava and sandstone | BLSD |
| Borax-stone - A type of non-carbonate salt that is composed of particles of the borate mineral borax. British Geological Survey Research Report RR/99/03, section 7.1 and fig. 11. | BORXST |
| Basaltic-rock, macroporphyritic (unclassed) | BRMA |
| Basaltic-rock, microporphyritic (unclassed) | BRMI |
| Basaltic-rock, plagioclase-olivine-clinopyroxene-macrophyric | BRPOCM |
| Basaltic-rock, plagioclase-olivine-clinopyroxene-phyric | BRPOCP |
| Basaltic tuff, hyaloclastite and basalt | BTHB |
| Lava, basaltic-trachyandesite | BTLAVA |
| Carnallite-stone - A type of non-carbonate salt that is composed of particles of the chloride mineral carnallite. British Geological Survey Research Report RR/99/03, section 7.1 and fig. 11. | CARNST |
| Rock, charnockitic - A type of coarse-grained normal crystalline rock. The charnockitic suite of rocks is usually characterised by the presence of orthopyroxene (or fayalite plus quartz, though in such assemblages fayalite is invariably altered) and, in many such rocks, perthite, mesoperthite or antiperthite. Primary hydrous minerals are generally absent. They are commonly associated with norites and anorthosites and are linked closely with high-grade metamorphic terrains. Despite being composed largely of feldspar and quartz, charnockitic rocks are generally melanocratic due to very dark feldspar crystals, which also have a characteristically greasy appearance. British Geological Survey Research Report RR/99/06, section 5.1. Examples (root name and qualifier): charnockitic granite, charnockitic monzonite, charnockitic tonalite. | CHARNR |
| Clarain - A type of bituminous-coal, classified according to lithotype. It consists of bright to semi-bright bands of finely laminated coal. Clarain generally exhibits an overall silky lustre, and commonly contains fine vitrain bands alternating with a duller attrital groundmass. British Geological Survey Research Report RR/99/03, section 6.1 and fig. 10. | CLARIN |
| Camptonite, monchiquite, basalt and basanite | CMBB |
| Camptonite, monchiquite and olivine basalt | CMBO |
| Colemanite-stone - A type of non-carbonate salt that is composed of particles of the borate mineral colemanite. British Geological Survey Research Report RR/99/03, section 7.1 and fig. 11. | COLEST |
| Dolerite and tholeiitic basalt | DBAT |
| Dolerite, feldspar-phyric, and basalt, feldspar-phyric | DFPBFP |
| Diamicton, pedogenically-altered | DMTNP |
| Eclogite - A type of metamorphic rock with unknown protolith based on modal composition. In the Rock Classification Scheme, it is defined as a rock composed of more than 70% garnet and jadeitic clinopyroxene (omphacite). Eclogites do not contain plagioclase. They may contain other anhydrous minerals such as quartz, kyanite, orthopyroxene and rutile, together forming no more than 30% of the rock. Eclogites result from metamorphism of basaltic or gabbroic igneous rocks under very low P.H20 producing anhydrous mineral assemblages. They define a unique eclogite facies metamorphism, typically reflecting very high pressures although their local occurrence within amphibolite facies rocks suggests they may be formed over a significant range of pressure. British Geological Survey Research Report RR/99/02, section 6.2. | ECLOG |
| Exotic crystalline igneous rock - These are the chemically and/or mineralogically exotic crystalline igneous rocks. In the Rock Classification Scheme, this class includes carbonatite, melilitic rock, kalsilitic rock, kimberlite, lamproite, leucitic rock, and lamprophyre. Rocks in these groups have sufficiently unusual mineral and chemical compositions that they are not classified using the modal (QAPF and ultramafic diagrams) or chemical (e.g. TAS) methods by which normal crystalline igneous rocks are classified. Although they comprise only a tiny proportion of all crystalline igneous rocks, the unusual characteristics and distinctive field settings of the exotic igneous rocks means they have attracted a large amount of attention from geologists. British Geological Survey Research Report RR/99/06, section 1.3 and fig. 1. | ECR |