Stones are still the main components of civil construction in world, with stones being used extensively in public buildings, hotels, temples, sculptures etc. It is increasingly being used in homes with the use of stones now penetrating amongst everyone. Natural Stones as the name suggests are naturally occurring and hence its structure, color, etc cannot be controlled.
Rocks are generally classified by mineral and chemical composition, by the texture of the constituent particles and by the processes that formed them. These indicators separate rocks into igneous, sedimentary and metamorphic. They are further classified is according to the particle size.
The transformation of one rock type to another is described by the geological model called the rock cycle. Igneous rocks are formed when molten magma cools and are divided into two main categories - plutonic rock and volcanic.
Plutonic or intrusive rocks result when magma cools and crystallizes slowly within the Earth's crust (example granite), while volcanic or extrusive rocks result from magma reaching the surface either as lava or fragmental ejecta (examples pumice and basalt).
Sedimentary rocks are formed by deposition of classic sediments, organic matter or chemical precipitates (vapours), followed by compaction of the particulate matter and cementation during diagenesis. Sedimentary rocks form at or near the Earth's surface.