Granite is a coarse-grained crystalline rock. Typical granite is composed of three minerals,—quartz, feldspar, and mica. Either hornblende or augite may occur with the mica or may replace the mica entirely. The prevailing color is imparted by the feldspar, which varies from red to pink. Some granite is very dark, while other is of a light gray color. The three minerals of which it is composed are mixed in varying proportions, one being sometimes almost wanting. Syenite is similar to granite except that it lacks quartz. In genuine granite the flakes of mica assume all positions. In case the flakes of mica are made to assume a parallel position, as by enormous pressure, giving the rock a slightly laminated structure, it becomes gneiss. Granite is an igneous rock formed by the cooling of molten masses. It is the chief rock of New England. New Hampshire is called the old Granite State. Geologists assert that granite hills may be recognized at a distance by their rounded form, resembling enormous bubbles.
Granite weathers, that is to say, disintegrates, very slowly. Granite hills are not, therefore, likely to be heavily clothed with vegetation. Although difficult to quarry and hard to dress, it is one of the most valuable building stones known. It neither crumbles, weathers, nor crushes. Granite buildings erected centuries ago show almost no perceptible change. A cubic foot of granite weighs from 165 to 170 pounds. Sandstone weighs from 130 to 160 pounds.
