GeoSnaps - Image of the Day
Geologic snapshots capturing Arizona’s geologic setting and mining history with a picture of the day from 1 January through 31 December 2013.
Check out previous GeoSnaps/Images of the Day.
March 2011 | Northern Black Mountains | Mohave County.
Dark-colored inclusions of fine-grained hornblende diorite contained within medium-grained biotite monzogranite of the Miocene-aged Mount Perkins pluton. Many of the inclusions have sharp chilled margins, notably darker and finer-grained than the interiors. They are interpreted as having formed from mafic magma emplaced into still-molten or only partially crystallized granitic host magma.
(Photo by Brad Johnson.)