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Foidolite

Igneous rock rich in feldspathoid minerals

Wikipedia contributorsAdapted for Fathomly · View authors
1 min read
Source updated May 13, 2026
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Foidolite (/ˈfɔɪdəlaɪt/) is a rare phaneritic (coarse-grained) intrusive igneous rock in which more than 60% (by volume) of light-coloured minerals are feldspathoids. Crystals of alkali feldspar, plagioclase, biotite, amphibole, pyroxene, and/or olivine may be present within the rock. The volcanic equivalents are termed foidite and phonolitic or tephritic foidites.

Some foidolites are a potential source of aluminium.

Thin section of foidolite under polarizing microscope. In the foreground there is a large yellow sodium pyroxene grain surrounded by fine grains.
Thin section of foidolite under polarizing microscope. In the foreground there is a large yellow sodium pyroxene grain surrounded by fine grains.
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This article is adapted from the Wikipedia article “Foidolite”, written by its contributors and licensed under CC BY-SA 4.0. Fathomly has changed the layout, removed citation markers, navigation and maintenance notices, and adjusted punctuation. This adapted version is shared under the same license. For references, see the original article.

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Related topics

QAPF diagram

A QAPF diagram is a doubled-triangle plot diagram used to classify igneous rocks based on their mineralogy. The acronym QAPF stands for "quartz, alkali feldspar, plagioclase, feldspathoid", which are the four mineral groups used for classification in a QAPF diagram.