Relating to or containing a group of light-colored silicate minerals that occur in igneous rocks, including minerals of the feldspathoid group and the minerals quartz, feldspar, and muscovite.
Relating to an igneous rock that contains a group of light-colored silicate minerals, including feldspar, feldspathoid, quartz, and muscovite.
(mineralogy) Enriched in the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium.
A rock with such properties.
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