Granite has been used as a building material since ancient times. It is one of the oldest and most durable building products available, and will far outlast the building in which it’s installed. It has become the material of choice for today’s luxury homes and offices because of its enduring beauty, resell value and because no synthetic material can yet compare to its elegance and performance. Products made of this stone will not depreciate with time and will continuously add value to any property where they are installed. Unlike synthetics, granite presents a surface depth that seems almost three-dimensional. It has a luminance that’s absent from other surfaces.
Granite, being an igneous rock (formed from volcanic activity), differs from marble, limestone, and travertine in that those are sedimentary stones composed mostly of calcite, a relatively soft and common mineral derived from animal skeletons and shells. Millions of years of compression and heat below the earth’s surface turned them into stone. Granite is one of the hardest stones available, having a rating of 7 on the Moh’s Measurement of Hardness Scale. In contrast, marble is rated only a 3.
Granite is sold both in tiles and slabs, and is frequently used not only for kitchen countertops, bar tops, and vanities, but also for walls, floors, fireplace surrounds, windowsills, and even building fascia. Its unique variations in color and veining turns make each specimen a natural work of art. It is cool to the touch, and presents an image of classic grace and beauty.
The word “granite” is used in a variety of ways by different people. A simple definition is used in introductory courses; 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 by people who sell dimension stone such as countertops, tile, and building veneer.
Introductory Course Definition: Granite is a coarse-grained, light-colored igneous rock composed mainly of feldspars and quartz with minor amounts of mica and amphibole minerals. This simple definition enables students to easily identify the rock based upon a visual inspection.
Petrologist’s Definition: Granite is a plutonic rock in which quartz makes up between 10 and 50 percent of the felsic components and 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. Many rocks identified as “granite” using the introductory course definition will not be called “granite” by the petrologist.
Commercial Definition: The word “granite” is used by people who sell and purchase cut stone for structural and decorative use. These “granites” are used to make countertops, floor tiles, curbing, building veneer, monuments, and many other products. In the commercial stone industry, a “granite” is a rock with visible grains that are harder than marble.
There are two obvious physical properties of granite that determine what it looks like: its texture (the size of the individual mineral grains) and its color. The variability in these two properties leads to a wide range of the appearance of granite.
The individual minerals in granite grow into visible grains because the magma cools slowly many miles below the surface. It is the size of the grains of different minerals that imparts the ‘speckled’ look to the rock.
Types of Granite Colors
Types of granite colors determine minerals and rocks that make granite. Quartz, amphiboles, feldspar, potassium, and mica (muscovite or biotite) minerals give granite such unique colors and patterns. Different types of granite colors depend on the concentration of these minerals in the stone. For example:
The combinations of these minerals give us different types of granite colors.
Due to its special climatic and geographical conditions, Iran is among the countries that are rich in natural resources and mines. In different parts of Iran, natural stone mines, especially granite, are found in abundance. Mines of this precious stone in cities such as; Hamedan, Mashhad, Natanz, Gilan, Nehbadan, Yazd, Zanjan, Khorramdareh, etc. are located. Granite extracted from each of these mines has different and varied textures and colors. This is the biggest advantage for the country. Because it has made Iran an exporter of granite to other parts of the world.