These include countertops, floor tiles, paving stone, curbing, stair treads, building veneer, and cemetery monuments. Granite is used all around us - especially if you live in a large modern city.
Granite is also well known from its many world-famous natural exposures. Yosemite Nature Notes - Granite: This video examines some of the granites that create the scenic and climbing pleasures of Yosemite National Park. Introductory geology textbooks report that granite is the most abundant rock in the continental crust. At the surface, granite is exposed in the cores of many mountain ranges, within large areas known as "batholiths," and in the core areas of continents known as "shields.
The large mineral crystals in granite are evidence that it cooled slowly from molten rock material. That slow cooling had to have occurred beneath Earth's surface and required a long period of time to occur. If these granites are exposed at the surface today, the only way that could have happened is if the granite rocks were uplifted and the overlying rocks were eroded. Most parts of Earth's continents are covered with sediments or sedimentary rocks.
The rocks below are usually granites, metamorphosed granites, or closely related rocks. These deep granites are often referred to as "basement rocks. Granite: Photograph of a white, fine-grained granite. Many of the grains in this rock can be seen with the unaided eye - especially the black grains.
However, the white grains are difficult to see with the unaided eye because their boundaries are difficult to recognize - even with help from a hand lens. This rock might be called an aplite because of its fine grain size. This specimen is about two inches across.
Granite close up: Magnified view of the white, fine-grained granite from the photograph above. You can see how it is difficult to recognize the boundaries between the light-colored grains - even with the help of magnification. A more precise definition is used by petrologists geologists who specialize in the study of rocks. And, the definition of granite expands wildly when used in the crushed stone and dimension stone industries.
These multiple definitions of granite can lead to communication problems. However, if you know who is using the word and who they are communicating with, you can interpret the word in its proper context.
Three common usages of the word "granite" are explained below. Generalized Composition Ranges of Common Igneous Rocks: This chart illustrates the generalized mineral composition of igneous rocks.
Granites and rhyolites compositionally equivalent to granite but of a fine grain size are shown on the left side of the chart. Granite is a coarse-grained, light-colored igneous rock composed mainly of feldspars and quartz; it also contains minor amounts of mica and amphibole minerals see the accompanying chart titled Generalized Composition Ranges of Common Igneous Rocks.
Once students know how to identify the minerals in granite, this simple description enables them to identify the rock based upon a visual inspection.
During that visual inspection, students should use a hand lens to confirm that the minerals of granite are present in the rock. That inspection would involve confirming that each of the minerals expected in granite is physically present in the rock - and present in the proper proportion. Feldspar minerals are abundant in granite. They are usually white, gray, pink or reddish in color.
Many grains will exhibit two directions of cleavage that intersect at right angles. You should be able to observe this cleavage pattern in granite with a hand lens. Quartz will usually be a transparent mineral that is colorless or gray in color. Many grains will exhibit a conchoidal fracture - with a vitreous luster on the conchoidal fracture surfaces.
The mica minerals expected in granites include muscovite or biotite. Micas occur in very thin sheets. They will often be in "books" of numerous sheets stacked upon one another. The surfaces of these sheets will have a highly reflective vitreous luster. The edges of a "stack of sheets" will look similar to the edge of a stack of playing cards.
Amphibole minerals such as hornblende are dark in color and will often have a prismatic habit. The best way to learn about rocks is to have specimens available for testing and examination. Basalt is commonly very fine grained , and it is nearly impossible to see individual minerals without magnification.
Basalt is considered a mafic silicate rock. Among other characteristics, mafic minerals and rocks are generally dark in color and high in specific gravity. This is in large part due to the amount of iron, magnesium, and several other relatively heavy elements which "contaminate" the silica and oxygen. But this heavy stuff really isn't happy near the surface, and will take any opportunity it can to head for deeper levels. The trick is to heat the basalt back up again so it can melt and give the iron another shot at the core.
It wants to be there, and heat is the key which unlocks the door. As it turns out , most of the ocean floor is basalt, and most of the continents are granite.
Basaltic crust is dark and thin and heavy, while granite is light and accumulates into continent-sized rafts which bob about like corks in this "sea of basalt. Not very pretty, but at least there's a clear winner.
And the seafloor basalt ends up in pretty much the same position as does the VW - under the truck or continent, as the case may be. This may seem like a drag for the basalt, but remember that it isn't all that happy on the surface anyway, and this gives it the heat it needs to re-melt and try to complete the differentiation process which was so rudely interrupted at the spreading ridge.
If successful and allowed to continue, what's left behind is a "purified" magma with most of the iron, magnesium, and other heavy elements removed. When it cools, guess what forms? Crushed limestone is by far the most commonly used crushed rock in the U. Crushed granite is used in road construction and railroad beds. Larger pieces of granite are used to stabilize the land around roadways to minimize and even eliminate soil erosion.
Please see either crushed stone or dimension stone for information about granite mining. There is an enormous abundance of granite throughout the United States, so it is not a surprise that a significant amount of granite is used in crushed stone applications. Granite is used extensively as dimension stone. It is used in the construction of buildings, both as building blocks and as veneers on frame structures.
Because it can be smoothed to a very high polish, granite has found extensive use in memorials, headstones, monuments, carved decorations on buildings, statues and the like. Approximately 1.
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