True granite is an igneous rock made up of mica, feldspar and quartz.
Most interesting among these are the Henry Mountains, formed by the intrusion of molten igneous rock between the layers of sediments, causing the overlying layers to arch up into dome mountains.
These clays are produced by the decomposition of the granite by acid vapours, which are discharged after the igneous rock has solidified ("fumarole or pneumatolytic action").
F. Magma is intruded into older rocks and crystallizes into a pink igneous rock called granophyre.
Orbicular granite - this igneous rock has an unusual orbicular granite - this igneous rock has an unusual orbicular structure that is sometimes seen in granites and diorites.