Keyword Definition

Fine-grained or porphyritic igneous rock with less than 20 percent quartz, and less than 10 percent feldspathoid minerals, in which the ratio of plagioclase to total feldspar is greater 0.65. Typically composed of calcic plagioclase and clinopyroxene; phenocrysts typically include one or more of calcic plagioclase, clinopyroxene, orthopyroxene, and olivine. Includes rocks defined modally in QAPF fields 9 and 10 or chemically in TAS field B as basalt. Basalt and andesite are distinguished chemically based on silica content, with basalt defined to contain less than 52 weight percent silica. If chemical data are not available, the color index is used to distinguish the categories, with basalt defined to contain greater than 35 percent mafic minerals by volume or greater than 40 percent mafic minerals by weight.

after LeMaitre et al. 2002

See Also: leuco-basalt, mela-andesite, picrite, picrobasalt

Parents: Basic igneous rock (27); Fine grained igneous rock (86)

Children: Alkali olivine basalt (3); Tholeiitic basalt (254)

[Description taken from GeoSciML SimpleLithology201012.rdf]

Hierarchical classification

Sample >> Lithosphere >> Rock >> Whole >> Rock >> Igneous >> Basic >> Basalt


Alkali olivine (basalt) | Tholeiitic

Category: Analysed material

The different kinds of sample material collected in the field have been classified hierarchically. Examples: “till”, “soil”, “vegetation”. Taken from the “Sample_Types_SHARED” database table.

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