Fine grained (igneous rock)

Keyword Definition

Igneous rock in which the framework of the rock consists of crystals that are too small to determine mineralogy with the unaided eye; framework may include up to 50 percent glass. A significant percentage of the rock by volume may be phenocrysts. Includes rocks that are generally called volcanic rocks.


Need to make decision as to whether devitrified glass should be considered glass or microcrystalline framework for purposes of categorization

Gillespie and Styles 1999; LeMaitre et al. 2002

Parents: Igneous rock (138)

Children: Andesite (11); Basalt (23); Dacite (68); Foiditoid (108); High magnesium fine grained igneous rock (132); Phonolitoid (194); Rhyolitoid (224); Tephritoid (253); Trachytoid (258)

[Description taken from GeoSciML SimpleLithology201012.rdf]

Hierarchical classification

Sample >> Lithosphere >> Rock >> Whole >> Rock >> Igneous >> Fine grained


Foiditoid | High magnesium | Phonolitoid | Tephritoid | Trachytoid

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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