The Scheme for Igneous Rock Identification

A Brief Tour

Grain Size Description Crystal size

Igneous rocks have “Intergrown Crystals”

Intergrown

Intergrown

Not Intergrown

Where it was formed Outside the volcano: Extrusive Inside the Earth: Intrusive Where it was formed

Bubbles? Yes= Vesicular

Bubbles? No=Non-vesicular

Color Neither Light nor Dark Very Light NotVery Light Not Very Dark Darkest Lightest

Medium Density Density Light Dense Very Dense

Finding The Minerals Unless you have other information, work in the middle of the rock’s box. Identify the rock.

This is the amount of Potassium Feldspar in the rock.

This is the amount of Quartz in the rock.

This is the amount of Plagioclase Feldspar in the rock.

Name a light-colored, fine-grained rock with no bubbles. Practice

Name a coarse-grained, dense rock.

Name a very light-colored, glassy, extrusive rock with bubbles.