Author:
Qjure
Book:
Qjurious
Type:
Info
Chapter:
1-40_.__.01
Trachyte
Mineralogy
An extrusive igneous rock composed mostly of alkali feldspar. It is usually light-colored and aphanitic (fine-grained), with minor amounts of mafic minerals, and is formed by the rapid cooling of lava enriched with silica and alkali metals.
It is the volcanic equivalent of syenite.
Content
Primary: Alkali feldspar
Secondary: Plagioclase, quartz, or feldspathoid.