Andesite


Andesite

Andesite

Extrusive igneous rock of intermediate composition.
Fine-grained, greenish/gray, compacted ash-fall (tephra) rock (lacks internal structure). Intermediate between andesite and dacite in color/appearance.
Miocene age or older volcanic source.
From Cady Mountains area, Mojave Desert, CA.

https://gotbooks.miracosta.edu/rocks/igneous/7.html

2/2/2021