Granite Facts

      Granite is a common and widely occurring type of intrusive, felsic, igneous rock.Since granite is formed in nature there are no two applications that are the same, each installation is unique. Every individual slab you  inspect will exhibit differences even if the slabs were cut from the same block. Even though the granite is given names, the names are just an indicator of the color, texture and veining , never an absolute. It is these natural differences that make granite unique, valuable and highly desirable. The poet Gerard Manley Hopkins in his poem Pied Beauty captured the essence of granite in the line "Glory be to God for dappled things." Granite is indeed a rare, unique gift of nature.

Granite is an intrusive (within the Earth’s crust) igneous rock; the formation occurs by magma flowing into pockets deep beneath the Earth’s surface and over millions of years cools and crystallizes. In some cases the stone could also go through a metamorphic change (exposure to high pressure and temperatures of a long period of time) resulting in a transformation of the crystalline structure. There are basically 25 minerals that can be found in granite each contributing to the color and physical make up of the stone. The four mineral families most commonly found are quartz, feldspar, mica and hornblende.

Granite is 2 cm and 3 cm represent the "standard" thicknesses for counter tops. The slabs are then sent through a seven stage polishing procedure to achieve the desired high gloss surface finish. High pressure is used in each of the seven stages of polishing. The polishing process will often dislodge softer minerals that are in the granite surface. The extent to which this pitting occurs is dependent upon the physical makeup of the granite. Granite minerals have a Moh’s scale hardness rating of 6 to 7 (Diamond is the hardest with a Moh’s hardness of 10). Biotite, a member of the mica family and frequently found in granite, has a Moh’s hardness of 2.5 to 4.5 and consequently does not polish well and will appear as small rough spots on the surface. The hardness of the biotite makes little difference in most applications, as the overwhelmingly dominant feldspar and quartz minerals are much harder. The biotite may "pluck" slightly when polishing but not in general use.

     Another naturally occurring phenomenon are fissures. Fissures are often confused with cracks as they appear on the surface of the granite. Fissures were created when the stone was first formed. There is a difference between a crack and a fissure. Fissures are naturally occurring and represent no issue in the performance of the stone. The only fissures that should appear on a grade A stone are found just on the surface. A mechanical force due to fabrication, installation or other circumstances at the job site causes a crack. The cracks caused by a mechanical force generally transmit entirely through the slab so it would appear on the top, edges and bottom of the slab.

     Once the slabs have been polished the surfaces are then sealed. The sealant adds an oliophobic and hydrophobic barrier on the surface of the granite that causes oils and water to bead. At this point the slabs are ready for shipment.

Some technical facts about granite:

     There are many questions regarding the potential for bacteria growth on granite since it is a porous material. Bacteria requires several things in order to thrive and grow: oxygen, water, sunlight, nutrients, and a substrate to form on. The minerals in granite are toxic to bacteria. As a result, there is no habitable environment for the bacteria to live and grow on a granite surface.