The granite group is one of the most versatile stone types available. (stone_buy)

Granite, and granite-like materials, are capable of taking a wide variety of finishes which allow the designer to custom-tailor the stone to the aesthetic or performance requirements of a specific application. (stone-buy)

Resistance to scratching and durability in foot traffic areas are largely dependent upon the hardness of the minerals that make up the stone. In most granites, the primary minerals are quartz and feldspars, accounting for approximately 90% of the stone. The hardness of a mineral is oftentimes defined by use of Moh's Scale of Relative Hardness, developed in 1822 by the Austrian Mineralogist Friedrich Moh. This scale lists 10 minerals in ascending order of scratch resistance:

1. Talc   2. Gypsum    3. Calcite   4. Fluorspar     5. Apatite
6. Feldspar 7. Quartz   8. Topaz   9. Corundum     10. Diamond

This scale can be further expanded by adding other minerals or common materials with scratch resistance that is similar to those minerals originally cited by Moh:

1. Talc, Sulpher   2. Gypsum, Amber   2½ Fingernail
3. Calcite, Coral (3-4), Pearl (3-4)   3½ Copper penny
4. Fluorspar, Fluorite, Rhodochrosite

5. Apatite, Turquoise (5-6)5½ Opal, Steel knife blade  

6. Feldspar 6½ Hardened steel file, Common window glass  

7. Quartz, Garnet, Beryl   8. Topaz   9. Corundum   10. Diamond

It should be noted that the above scales are of "relative" hardness, and not linear. As example, there is significantly less difference between 7 and 8 on the list than there is between 9 and 10. What the scale does tell us is that a mineral that can be scratched with a fingernail has a hardness of less than 2½. A mineral that can be scratched with a pocketknife, but not with a penny, has a hardness of between 3½ and 5½. Feldspar and quartz, with hardness of 6 & 7 respectively, are the minerals that give granite its exceptional abrasion resistance. This abrasion resistance contributes to its long service life in high traffic areas of public buildings.

The dimensional stability of granite is very good, so good in fact, that granite is the material of choice for high precision applications such as surface plates, machine mounts and press rolls, where tolerances can be measured in micro-inches (millionths of an inch). Granite, 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 dimension stone panels, this means that a 5' 0" [1524 mm] panel would change dimension by approximately 0.026" [0.67 mm] in a 100 [56] 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 [250]).