Granite - the science bit
Granite is a common and widely occurring type of igneous rock. Granite has a medium to coarse texture. Granites can be pink to dark gray or even black, depending on their chemistry and mineralogy. Granite is nearly always hard and tough, and therefore it has gained widespread use as a construction stone.
The word granite comes from the Latin granum, a grain, in reference to the coarse-grained structure of such a crystalline rock.
Granite is currently known only on Earth where it forms a major part of continental crust. Granite often occurs as relatively small, less than 100 km² stock masses that are often associated with orogenic mountain ranges.
Granite has been intruded into the crust of the Earth during all geologic periods, although much of it is of Precambrian age.
Granitic rock is widely distributed throughout the continental crust of the Earth and is the most abundant basement rock that underlies the relatively thin sedimentary veneer of the continents.
Use in Building
Granite has been extensively used as flooring tiles in public and commercial buildings and monuments for many years.
Because of its abundance, granite was commonly used to build foundations for homes. The Granite Railway, America's first railroad, was built to haul granite from the quarries in Quincy, Massachusetts, to the Neponset River in the 1820s.
With increasing amounts of acid rain in parts of the world, granite has begun to supplant marble as a monument material, since it is much more durable. Polished granite is also a popular choice for kitchen countertops due to its high durability and aesthetic qualities.
Use in Sport
Curling stones are traditionally fashioned of Ailsa Craig granite. The first stones were made in the 1750s, the original source being Ailsa Craig in Scotland.
Use in Engineering
Engineers have traditionally used polished granite surfaces to establish a plane of reference (flat surface), since they are relatively impervious and inflexible. Sandblasted concrete with a heavy aggregate content has an appearance similar to rough granite, and is often used as a substitute when use of real granite is impractical.
A most unusual use of granite was in the construction of the rails for the Haytor Granite Tramway, Devon, England, in 1820.
Marble - the science bit
Marble is a metamorphic rock resulting from regional or rarely contact metamorphism of sedimentary carbonate rocks, either limestone or dolomite rock, or metamorphism of older marble. This metamorphic process causes a complete re crystallization of the original rock into an interlocking mosaic of calcite, aragonite and/or dolomite crystals. The temperatures and pressures necessary to form marble usually destroy any fossils and sedimentary textures present in the original rock.
Pure white marble is the result of metamorphism of very pure limestone's. The characteristic swirls and veins of many coloured marble varieties are usually due to various mineral impurities such as clay, silt, sand, iron oxides, or chert which were originally present as grains or layers in the limestone. Green coloration is often due to serpentine resulting from originally high magnesium limestone or dolostone with silica impurities. These various impurities have been mobilized and re crystallized by the intense pressure and heat of the metamorphism.
Where Some Marble Comes From
| Marble name/Colour | Location |
|---|---|
Carrara marble/white or blue-gray |
Carrara Italy |
Parian marble/Fine-grained semi translucent pure-white |
Island of Paros Greece |
Rouge de Rance/Red |
Rance Belgium |
Macedonian Bianco Sivec/White |
Prilep Republic of Macedonia |
Tennessee marble/Pale pink to cedar-red |
Knox, Blount and Hawkins Counties, Tennessee US |
Yule/Uniform pure white |
Marble, Colorado US |
As the favourite medium for Greek and Roman sculptors and architects, marble has become a cultural symbol of tradition and refined taste. It's extremely varied and colourful patterns make it a favourite decorative material.
Use in Industry
As well as a building material there are other uses of marble.
Colourless or light coloured marbles are a very pure source of calcium carbonate, which is used in a wide variety of industries. Finely ground marble or calcium carbonate powder is a component in paper, and in consumer products such as toothpaste, plastics, and paints.
If you would like to know more about the formation and use of Granite and Marble Products please go to the Free Encyclopedia Wikipedia.org
To Save time, here's the links directly to Granite and Marble in the Wikipedia website.