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Marble is a rock widely used in buildings, monuments, and sculptures. It consists chiefly of calcite or dolomite, or a combination of these carbonate minerals. Marble is a type of metamorphic rock formed from limestone. Marble is found in many countries, including Belgium, France, Great Britain, Greece, India, Italy, and Spain.

Marble is formed from limestone by heat and pressure in the earth's crust. These forces cause the limestone to change in texture and makeup. This process is called recrystallization. Fossilized materials in the limestone, along with its original carbonate minerals, recrystallise and form large, coarse grains of calcite. Impurities present in the limestone during recrystallization affect the mineral composition of the marble that forms. The minerals that result from impurities give marble wide variety of colours. The purest calcite marble is white. Marble containing hematite has a reddish colour. Marble that has limonite is yellow, and marble with serpentine is green.

Granite is a hard, coarse-grained rock that makes up a large part of every continent. Granite contains three main minerals - quartz, alkali feldspar, and plagioclase feldspar. These minerals make granite white, pink, or light grey. Granite also contains small amounts of dark brown, dark-green, or black minerals, such as hornblende and biotite mica. The grains of the minerals in granite are large enough that they can easily be distinguished.

The minerals in granite are interlocked like the pieces of a jigsaw puzzle. Consequently, granite is a strong and durable which makes it useful for construction.

Geologists classify granite as an igneous rock. The slow cooling and crystallization of molten material called magma forms most granite. Magma has the same chemical composition as granite. It forms from rocks that melt 16 to 25 miles (25 to 40 kilometers') below the surface of the continents. These rocks melt at temperatures between 1200' and 1650' F. (650' and 900' C). As the magma rises, it cools. Most granite magma cools slowly enough to form coarse crystals and it solidifies below the earth's surface. Sometimes granitic magma erupts from volcanoes and cools too quickly to form large crystals. The resulting rock, called rhyolite, has the same mineral composition as granite but is fine grained.

Limestone is a type of rock made up mostly of calcite, a mineral form of calcium carbonate. Most limestone is grey, but all colours of limestone from white to black have been found. All limestone are formed when the calcium carbonate crystallises out of solution. It leaves the solution in many ways, and each way produces a different kind of limestone.

Limestone can be formed almost completely without the aid of organisms. This type of limestone is forced out of solution when the water evaporates.

Evaporation of water in limestone caverns forms another variety of limestone, called travertine, into stalactites and stalagmites.

Sandstone is a type of rock composed mainly of sand that has been 'bonded' together by pressure or by minerals. The sand commonly consists of grains of quartz, feldspar, and other minerals. It may also include organic matter or rock fragments. The minerals that cement the grains include quartz, pyrite, or calcite.

The colour of sandstone ranges from cream or grey to red, brown, or green, depending on the cements and impurities in the sand. Brownstone, reddish-brown sandstone, was once widely used to build houses. Sandstone was a common building material for larger structures before reinforced concrete came into use in the middle to late 1800's.

Slate is a fine-grained rock that can easily be split into thin, durable sheets. It consists mainly of grains of mica and quartz, plus smaller amounts of chlorite, hematite, and other minerals. Most slate is grey to black in colour, but the rock may be red or purple, depending on its mineral content.

Slate is a metamorphic rock. Most slate is formed below the earth's surface by changes in the makeup and appearance of shale, a sedimentary rock. Shale consists of clay and fine particles of quartz. Heat from deep in the earth changes some of the clay in shale into mica and chlorite. Slate results when pressure created chiefly by mountain-forming movements in the earth's crust squeezes the mica and other minerals into parallel layers.

The building industry uses slate for roofing and flagstone because the rock is weatherproof and long lasting. Slate is also used to trim the fronts and lobbies of buildings.