Granite is a hard, coarse grained rock that makes up a large part of every continent. Granite contains three main minerals, quartz, alkali feldspar, and plagioclase feldspar. These minerals make granite white, pink, or light grey. Granite also contains small amounts of dark brown, dark green or black minerals, such as hornblende and biotite mica. The grains of the minerals in granite are large enough that they can easily be distinguished.
The minerals in granite are interlocked like the pieces of a jigsaw puzzle. Consequently, granite is a strong and durable. Geologists classify granite as an igneous rock. The slow cooling and crystallization of molten material called magma forms most granite. Magma has the same chemical composition as granite. It forms from rocks that melt 16 to 25 miles below the surface of the continents. These rocks melt at temperatures between 1200 and 1650 degrees Fahrenheit. As the magma rises, it cools.
Most granite magma cools slowly enough to form coarse crystals and it solidifies below the earth’s surface.
Sometimes granite magma erupts from volcanoes and cools too quickly to form large crystals. The resulting rock, called rhyolite, has the same mineral composition as granite but is fine grained.
Amazon Green |
American Black |
Autumn Rose
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Blue Topaz
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Carnation Pink
|
Cloud Gray
|
Confetti Black
|
Dakota Red |
Black Diamond |
Evergreen |
Flash |
Galaxy Black |
Gray Cloud |
Gray Forest |
Imperial Red |
India Red |
Keystone Blue |
Keystone Green |
Leopard Spot |
Medium Barre Gray |
Missouri Red |
Multi-Swirl |
Night Black |
North American Pink |
Paradise Green |
Red Swirl |
Riverbed Brown |
Riverbed Red |
Sagebrush |
Salisbury Pink |
SD Pink |
Seashell Pink |
St. Alban's Pink |
Super Gray |
Topaz Blue |
Wassau Red |