Which minerals are present in granite

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. Skip to content Return to Minerals Database.

Type Rock. Related topics: Mica. Volcano Coloring Page. Rock Odyssey Poster. Dimension Stone. Granite is one of the most commonly known types of rocks, used in everything from buildings to sculptures. It has been used for thousands of years and is regarded as a symbol of status, strength, and durability. Granite is an intrusive igneous rock with large grains minerals easily seen by the naked eye. Granite colors are most commonly pink, white, variations of grey and black.

Granite is a conglomerate of minerals and rocks, primarily quartz, potassium feldspar, mica, amphiboles, and trace other minerals. The minerals that make up granite give it the unique colors we see in different types of granite.

The relative proportion of different colored minerals in a granite is largely due to the original source of molten rock that cooled to form the granite. If the molten rock was abundant in potassium feldspar, the granite is more likely to take on a salmon pink color.

On the other hand, if the molten rock is abundant in quartz and minerals that make up amphibole, you will likely get a black and white speckled granite commonly seen on countertops. The combination of the minerals above make up most of the colors we typically see in a granite. Now, let's break down the distance types of granite and a quick overview of what gives them their color. White granite is a granite that is composed primarily of quartz milky white and feldspar opaque white minerals. The small black specks in the granite above are likely small amphibole grains.

This could be due to a lack of chemical components needed to form amphibole, or the cooling process was not amenable to formation of amphiboles. Most commonly, black granite is in fact gabbro, a mafic intrusive igneous rock similar to basalt.

Gabbro is primarily composed of minerals pyroxene, plagioclase, and small amounts of olivine dark green and amphibole. Pink colored granite is a result of an abundance of potassium feldspar within the granite. However, in a granite like the one above the primary mineral is potassium feldspar. The above granite appears to have equal parts quartz, feldspar, and amphibole, making a speckled black and white granite.

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.

Granite is a plutonic rock in which quartz makes up between 10 and 50 percent of the felsic components. Alkali feldspar accounts for 65 to 90 percent of the total feldspar content. Applying this definition requires the mineral identification and quantification abilities of a competent geologist. This type of analysis cannot be done precisely by a student in a classroom or a geologist in the field. This is an example of the complexities that can be involved in assigning a formal name to an igneous rock.

Many rocks identified as "granite" using the introductory course definition will not be called "granite" by the petrologist. They might instead be alkali granites, granodiorites, pegmatites , or aplites. These names are for specific types of granite. These names require a consideration of the grain size and the mineral composition of the rock - beyond determining that the rock is a granite.

A petrologist might call these "granitoid rocks" rather than granites. There are many types of granite based upon mineral composition and texture. The accompanying chart Generalized Composition Ranges of Common Igneous Rocks illustrates the range of granite compositions. From the chart you can see that orthoclase feldspar , quartz , plagioclase feldspar , micas, and amphiboles can each have a range of abundances.

Using the terminology of geologists, they would be clockwise from top left : granite , gneiss , pegmatite , and labradorite. Click on any of their names above for an enlarged view. Each of the images above represents a slab of polished rock about eight inches across. Use of the word "granite" in the dimension stone and crushed stone industries is different from how the word is used by geologists. In these industries, the name "granite" refers to an igneous rock that meets the following criteria:.

Using these criteria, gabbro , basalt , pegmatite , schist , gneiss , diabase , diorite , and many other igneous rocks will be called "granite.

These "granites" are used to make crushed stone that is used for highway construction, concrete, building construction, fill, railroad ballast, and many other purposes. They are used in the dimension stone industry to make countertops, floor tiles, curbing, building veneer, monuments, paving stones, and many other products. These granites might be used with sawn, sheared, or polished surfaces.

Pegmatite: Photograph of a granite with very large crystals of orthoclase feldspar. Granites composed mainly of crystals over one centimeter in diameter are known as "pegmatites. Granitic rocks: This triangular diagram is a classification method for granitic rocks. It is based upon the relative abundance of feldspars K-Na-Ca and quartz.