Texture is the overall size, shape, and arrangement of the mineral grains that make up the rock. There is a crude correlation between the color of the rock and its composition. Rocks containing more silica, such as granite and rhyolite, are generally lighter in color. A simplified igneous rock classification chart is included as well as a percentage composition chart. These may be reproduced for student use.
Maine is rich in igneous rock bodies.
These rocks have provided the basis for much of the mining and quarrying activity that has taken place in the state over the years. Gem tourmalines, aquamarines, topaz, and other gem materials are found in Maine's igneous rocks. The Sebago Lake and Bottle Lake batholiths, which were proposed sites for radioactive waste storage facilities, are igneous rock formations. Mount Katahdin and Mount Desert Island, two of the state's premier natural attractions, are essentially igneous in composition. See suggested list below.