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.
Granite, like other building stones, is used for a variety of structural and decorative purposes.
Typical exterior uses for granite include:
structural and veneer building stone
paving and curbstones, and
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