Three types of stone are used in building materials: igneous, sedimentary and metamorphic. Different construction projects call for materials with different degrees of hardness, durability and cosmetic appeal. Knowing some of the rocks from within each of these categories helps you better understand why different types of rock are used for different projects.
Granite is a widely occurring form of igneous rock. Granite is formed by magma and found in the continental plates of the earth's crust. Granite does contain uranium, so it does give off natural radiation, but is generally considered to be safe for use in construction. Granite can be pink to grey in colour, with a medium to corse texture. Granite is often polished when used in construction to make it more durable and aesthetically appealing. It is most commonly used for countertop and floor surfaces.
Sandstone is a sedimentary rock formed by microscopic grains of rocks and minerals such as quartz and feldspar. Sandstone comes in an array of colours including the most commonly-seen brown, tan, yellow, pink, red, white and grey. Sandstone is preferred for use in building because it is weather-resistant, yet easy to work with. It is also a porous and heat-resistant rock making it ideal for floors, walls, fireplaces and pavers.
Slate is a type of sedimentary rock formed from clay and volcanic ash. Slate is most commonly seen in shades of grey, but is also seen in varying shades of blue, green and purple. It is extremely hard and non-porous. Slate is most commonly used for roofing tiles, floor tiles and pavers.
Made from re-crystallised carbonate minerals such as calcite or dolomite, marble is a metamorphic rock. Marble is non-porous and weather resistant, which makes it ideal for use in construction. White is the most common colour of marble, but it also comes in shades of grey, pink, green, blue, black, brown and yellow. When used in construction, marble is typically polished to make it more aesthetically appealing and durable. It is used for countertops, floors and a variety of decorative finishings.