Choosing a countertop for your kitchen can be a fun and eye-opening experience, especially when you realize how many incredible choices there are with Granite.
Inspiring Colors: Hot red granites swirling with black and gray veins… peaceful blue granites patterned like waves of sand… deep green granites with sparkles of translucent quartz and silvery mica…. These are the works of art that await you, if you’re willing to look for them.
Traditional Favorites: Looking for something a touch more conventional? You’ll find that too. Patterned beige, gold, and brown granites blend well with just about any color scheme. There are also perfectly black granites, others with copper-colored accents, and even white granites that look like vanilla ice cream with caramel swirls!
What is Granite
The definition of granite from a geological standpoint is “any plutonic rock in which the mineral quartz is 10 to 50 % of the felsic components, and the ratio of alkali to total feldspar, is between 65 and 95 %.” Commercially, any holocrystalline quartz-bearing plutonic rock is generally included in the granite rock grouping.
Granite is considered to be one of the most versatile types of natural stone available. Tiles slabs and countertops are available in a wide range of granite colors. Natural stone fabricators or granite fabricators, can custom-tailor the stone to the aesthetic or performance requirements requested.
It should be noted that the above scales are of “relative” hardness, and not linear. For example, there is significantly less difference between 7 and 8 on the list, than there is between 9 and 10. The scale tells us that a mineral that can be scratched with a fingernail has a hardness of less than 2½. Minerals that can be scratched with a pocketknife, but not with a penny, offer a hardness of between 3½ and 5½. Quartz and Feldspar, with hardness of 6 & 7 respectively, are the minerals that give granite its exceptional abrasion resistance.
Granite offers excellent dimensional stability. In fact, it is so good, that granite is the material of choice for many precision applications such as machine mounts, surface plates and press rolls, where tolerances can be measured in micro-inches (millionths of an inch). Granite, just like any solid, will expand and contract with changes in temperature. This change is relatively small. The coefficient of linear thermal expansion of granite is typically in the neighborhood of 4.4 x 10-6 inches per inch per degree Fahrenheit. In the perspective of common stone panels, this means that a 5′ 0″ panel would change dimension by approximately 0.026″ in a 100°F temperature change. Granite will typically return to its original dimension when the original temperature is reestablished. Permanent strain, or failure to return to its original dimension will not normally occur unless the material has been heated to excessive temperatures (above 480°F ).
Granite Acid Resistance
Industrial processing vats containing sulfuric acid, hydrochloric acid, nitric acid, and bromine are commonly lined with granite panels, taking advantage of the material’s natural resistance to these caustic chemicals. This level of chemical resistance contributes to the ability of granite to resist attack from airborne pollutants associated with acid rain and/or snow-melting chemicals. Certainly there are chemicals that will attack granite, but exposure to them in a typical building environment would be extremely rare.
Granite Flexural Strength
Flexural strength, or the ability to resist bending force, is a factor that determines the allowable span of a dimension stone panel in a given thickness subjected to given loads. Flexural strength varies amongst different types of granite, and typically is between 1,000 and 2,000 lbs/in². This allows the use of “thin” (30 mm) panels for many applications, minimizing both curtain wall cost and dead load for the building frame. Thicker granite panels (15/8″ [40 mm], 2″ [50 mm] or greater) are available where spans or loads necessitate their use.
Granite Water Absorption
For applications that are below grade or in contact with soil, water absorption is an important property. Absorption rates of granites range from 0.10% and 0.40% by weight. Furthermore, most granite materials will effectively allow water to evacuate during freezing cycles to prevent surface damage from the freezing water. Repetitive freeze/thaw cycles, particularly saturated cycles, will result in a reduction of strength in the granite panel. This loss can be significant, perhaps 20%. Laboratory experiments have shown that the strength loss occurs most aggressively in the first 100 cycles, after which the strength loss is much slower paced.
Granite Direct, Denver, Colorado