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Stone is a naturally occurring material that man has made use of since the beginning of time. Different types of stone exist on the Earth’s surface, having been formed over millions of years and by natural processes. There are many different kinds of stone that are used by people for many purposes and have been intrinsically linked to technological and cultural developments in the human race.
One of the main uses of natural stone is for building and paving. When used in an appropriate setting, a carefully selected stone material can enhance the look and value of a property as well as being extremely durable and, on the whole, maintenance-free.
Types of stone and their formation
In general, all rocks can be classified in one of three categories:
Igneous – rocks formed from cooled magma (e.g. from volcanoes) from the earth’s core.
Sedimentary – rocks are formed from the deposits of sediments and organic matter under pressure over a considerable period of time.
Metamorphic – this type of rock is made from rocks that have previously been formed but have since been placed under different pressures and conditions.
Within these three main categories, rocks can further be divided into sub-categories according to grain size/appearance etc
Types of natural stone and uses
Granite – an igneous rock that contains mineral crystals such as quartz. It comes in many colours and grain patterns and can be very highly polished to a mirror effect. Granite is a very strong, impervious stone. It is widely used for flooring, kitchen worktops and building facades.
Sandstone – a sedimentary rock which has a grainy texture. It comes in many different colours dependent on the dominant mineral in its composition. It is held together by natural cement. It is very popular as a building and flooring material and can be used for ornate or carved finishes. Most sandstones have good load bearing and weathering properties.
Limestone – a sedimentary rock that has an extensive range of colours depending on where it was extracted. Limestone can be used for walls and flooring. It is also extensively used for decorative aspects of buildings as well as window ledges, lintels and copings. It has good load-bearing properties. It weathers well but some types can be susceptible to the effects of pollution.
Slate – generally accepted as being a metamorphic stone. It has a smooth texture and can be cleaved into thin sheets for use as roofing material, work surfaces and flooring. Slate is a very durable material for building and has excellent stability, for example it doesn’t warp.
Marble – a metamorphic rock formed from limestone and re-crystallised minerals. Marble is white, but due to impurities, discolouration and veining is common. It is widely used for decorative purposes, flooring and building facades. If used for flooring, care should be taken to ensure an anti-slip surface.
Green Marble (Verde) – is slightly different from marble because it is made from non-limestone rocks. It is not as strong as normal marble and needs to be reinforced. It is used for flooring.
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