Granite

As mentioned in the general information about rocks, granite is an igneous rock that forms from molten rock (magma) deep underground. Granite is made up of feldspar, quartz, and mica, with feldspar being the biggest percentage and mica being the smallest. The White Mountains in the White Mountains National Forest in New Hampshire include an example of a large deposit of granite called a batholith. The name comes from the Greek words for “depth rock” because of where granite forms, deep in the Earth. Many other granite batholiths dot our planet, from Patagonia to Pike’s Peak, and Donegal, Ireland, to Darling, South Africa. Because it’s so common, you may have seen several different-colored stones called granite: it can be reddish or pinkish, it can be mostly white or light gray, or it can look dark gray. When it’s reddish or pinkish, that’s because it has red or pink feldspar in it. If it’s white or light gray, it has white feldspar in it, and the kind of mica it has in it is mostly muscovite. If it looks dark gray, because it has lots of small black pieces in it, the kind of mica in it is mostly biotite, which contains a lot of iron (Fe). Whatever color it might be, granite is a hard rock that’s very useful for building buildings, monuments and statues, stone stairs, the curbs along the side of the road, etc.

Rarity

Color

Value

Habit

Where Found

Formula Rock TypeShapeHardnessSpecific GravityStreakLuster
—Igneous—6–72.6–2.7——

Rock Gallery

Photo by: © Carl Quesnel
Photo by: © Carl Quesnel
Photo by: © Carl Quesnel
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