All About Granite

  • Posted on: 21 April 2012
  • By: admin

Granite is nearly always massive (lacking internal structure), hard and tough and therefore, it has gained widespread use as a construction stone. The average density of granite is 2.75 g/cm3, with a range of 1.74 g/cm3 to 2.80 g/cm3. The word ‘granite’ comes from the Latin ‘grnum’ meaning’ a gain’ in reference to the coarse-grained structure of such a crystalline rock.

Because of its nature, granite is very popular as a dimension stone and as flooring tiles in public and commercial buildings and monuments. With increasing amounts of acid rain in parts of the word, granite has begun to supplant marble as a monument material, since it is much more durable. Polished granite is also a popular choice for kitchen countertops due to its high durability and aesthetic qualities.

This is the reason that among the several flooring options in the market, granite is still the most sought after. It is available in two alternatives: slabs and tiles.

Granite Composition
Granite, the hard, natural, igneous rock with a visible crystalline texture is essentially formed of quartz and orthoclase or microcline. The principle constituents of granite are feldspar, quartz, and biotite. However, the percentage composition of each varies and imparts a different colour and texture to the final product. The percentage composition of feldspar varies between 65% to 90% quartx can extend from 10% to 60% while that of biotite lies between 10% and 15%.

Granite chemical properties
Granite is primarily composed of feldspar and quartz, along with various other minerals in varying percentage, which are stated are as under:

Nominal chemical composition of various oxides

Silica (SiO2) : 70 - 77 %
Alumina (Al2O3) : 11 - 14 %
Potassium Oxide (P2O5) : 3 - 5 %
Soda (Na2O) : 3 - 5 %

Lime : 1 %
Iron (Fe2O3) : 1 - 2 %
Iron (FeO) : 1 - 3 %
Magnesia (Mg) : 0.5 - 1 %
Titina : Less than 1 % (0.38 %)
Water (H2O) : 0.03 %

Granite physical properties
According to a stone website, granite has almost negligible porosity, ranging between 0.2 % and 4 % it is highly stable thermally, and therefore, shows no changes with change in temperature. Granite is impervious to weathering from temperature and even from air –borne chemicals. The high resistance to chemical erosion makes granite useful for making tanks to stone highly caustic material. The co –efficient of expansion for stone various from 4.7 x 10 -6 – 9.0 x 10 – 6 (inch x inch). Granite, the hardest building stone, shows consistency in colour and texture, and its hardness lends it excellent wear.

“Granite makes for excellent building construction material. It’s hard, resistant to weathering in a major way, and also available in an array of colours,” says an architect. “It‘s no wonder that it’s finding use so often in major construction projects – be it institutes, hotels or monuments.”

Mining and processing
A Granite quarry is a pit or some open excavation area from which granite is obtained. To obtain granite from a quarry, the methods of digging, cutting or blasting process, are used. This process of obtaining the stone is called ‘quarrying ‘.
Once quarrying is done, the processing of granite starts.

Processing involves four operations:


•Cutting / sawing

•Surface grinding and polishing

•Edge – cutting and trimming.
Once the processing is over, the granite is ready for further use.