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Government Resources: Environment, Climate, Geology, Energy, Wildlife and Ecology: Granite

What is Granite?

Granite is one of the most durable stones used in artistic and  architectural applications, including outdoor sculpture.  Granite is defined by the American Society for Testing and Materials (ASTM)  as a "visibly granular, igneous rock generally ranging in color  from pink to light or dark grey, and consisting mostly of quartz  and feldspars, accompanied by one or more dark minerals".  The  definition goes on to point out that "some dark granular igneous  rocks, though not properly granite, are included in the  definition."  Some dark colored igneous rocks which are actually  basalt, gabbro, dionite, diabase and anorthosite are quarried and  sold as "black granite."  These stones contain little or no quartz  or alkali feldspars, but, for all practical purposes, they are used  interchangeably with true granites.

 In addition to the quartz and feldspars, granite may also contain  other minerals such as mica, horneblend and occasionally pyroxene.  Compared to  calcareous sandstones, marble and limestone, granite  is not an acid soluble stone and is much more resistant to the  effects of acidic solutions, rainwater or cleansing agents.  In  general, igneous building stones, such as granite, have a more  inert composition; show much lower rates of deterioration; have  lower water absorption, and are harder than marbles, limestones and  sandstones.  Source:  Granite: Characteristics, Uses And Problems, GSA.

Uses of Granite

Granite, like other building stones, is used for a variety of structural and decorative purposes. 

Typical exterior uses for  granite include:


sculpture bases

structural and veneer building stone

architectural trim

paving and curbstones, and

grave markers.


Some applications, especially the simpler or more limited ones, can  be monolithic, however most uses will require the joining of  smaller pieces through various mechanical methods.  Joining methods  and techniques must be identified and evaluated as an integral part  of the evaluation of the system of construction, because of the  integral role of the joint in maintaining the soundness of the  system.  Source: Granite: Characteristics, Uses And Problems



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