Image credit: Scott Brande
Video Introduction to Igneous Rock Classification
Watch this short video for an introduction to a simplified classification of the common igneous rocks.
Simplified Classification of Common Igneous Rocks
Nature's production over time of molten material is prodigious and widespread. A consequence of the heterogeneous composition of the planet is a bewildering diversity of chemical compounds in igneous rock. A second factor in the classification of igneous rock is the control of texture by the diversity of environments in which molten rock solidifies. These two factors have resulted in highly specialized classifications in which rock names are arbitrarily assigned to narrow ranges of chemistry and texture.
As noted on the Home Page, this online study guide is being developed for students in a first introduction to physical geology. A necessity for a first introduction to the classification of the common igneous rocks is simplification, a loss of some accuracy, and the omission of significant details. A textbook or other references may be used as supplements to provide the additional knowledge lacking here.
The simplified classification table presented below focuses on features that may be observable without additional equipment (e.g., no hand-lenses, thin-sections, polarizing microscopes). As noted before, an advantage of digital online media is that images and video may be processed (e.g., zoomed) to partially substitute for the lack of hand lenses and low power microscopes.