IntroductionStone has been used as a building material for thousands of years. It has long been recognised as a material of great durability and superior artistic quality, the foremost choice for buildings associated with status, power and religion. The pyramids in Giza, Burial Chambers in the UK and The Prehistoric Temples Of Malta were all built from stone over 4000 years ago and are still standing. The use of stone in construction has declined over the last hundred years, but it remains an aristocrat of building materials. Building stone derives from one of three naturally occurring rock types: Igneous rocks: Rrocks are buried deep within the Earth, they melt because of the high pressure and temperature; the molten rock (magma) can then flow upward or even be erupted from a volcano onto the Earth's surface. When magma cools slowly, usually at depths of thousands of feet, crystals grow from the molten liquid, and a coarse-grained rock forms. The best example is Granite. When magma cools rapidly, usually at or near the Earth's surface, the crystals are extremely small, and a fine-grained rock results. The fame example is Basalts. A wide variety of rocks are formed by different cooling rates and different chemical compositions of the original magma. Both varieties correspond to a hard and non-porous rock. Sedimentary rocks: are formed at the surface of the Earth, either in water or on land. They are layered accumulations of sediments-fragments of rocks, minerals, or animal or plant material. Most sedimentary rocks become cemented together by minerals and chemicals or are held together by electrical attraction; some, however, remain loose and unconsolidated. Consolidate Sedimentary rocks are Soft and fairly porous rock widely used as building materials, the best examples are sandstone and limestone. Metamorphic rocks: Hard and non-porous rock formed from pre-existing rock that has been transformed by intense heat or pressure within the Earth's crust. The process of metamorphism does not melt the rocks, but instead transforms them into denser, more compact rocks. New minerals are created either by rearrangement of mineral components or by reactions with fluids that enter the rocks. Some kinds of metamorphic such as gneiss and biotite schist are two strongly banded or foliated. Pressure or temperature can even change www.intechopen.com Laser Scanning, Theory and Applications 328 previously metamorphosed rocks into new types. The most metamorphic rocks used in construction are marble and slate. There are huge variations within each of these rock types, caused by specific mineralogy and geology conditions, and while any stone can be used for building, they each have constraints that make them more or less suitable for different purposes. Granite, sandstone and limestone can all be used for building walls, but slate is only suitable for roofs and floors. Some types of granite can contain mineral salts that cause spalling, where the outer face of stone falls off; slate can contain harmful minerals that break down on ex...
