What is Granite?
Granite is an igneous rock. It is formed as a result of the slow crystallization of molten magma deep in the earth's crust. Uplift and erosion has over millions of years resulted in this material outcropping to the surface. The minerals, which make up granite, are generally quartz, feldspars, and other minerals. It is the size, distribution and precise chemistry of these materials that give granite its color. Granite can be worked to achieve finishes such as hand-tooled, flame textured, shot blasted, acid washed, honed or polished to a mirror finish. An excellent choice for kitchen counter tops.
What is Marble?
Geologically this is a limestone that has re-crystallized through the action of heat and pressure (metamorphism) while still retaining properties of the original material (i.e. its chemistry and possibly its relic sedimentary structures). Marble takes on an excellent polish and is available in a wide range of colors, patterns, and veining characteristics. Composed essentially of calcite, natural weathering processes will cause marble to lose their color and polish quite quickly compared to granite. Because of this, it is primarily used on indoor applications. Marble is idea for bathroom and fireplace applications.
What is Limestone?
This material was originally deposited as soft sediments being laid down as beds under water by a variety of chemical, biological, and physical processes. Over millions of years the sediments were buried, compressed and became cemented by precipitation from mineral waters contained therein. The majority of limestones are composed of calcium carbonate. Dolomite limestones are chemically magnesium carbonate. Limestone that has a porosity of 5% and takes a full polish is termed hard limestone (i.e. travertine). Primarily used for flooring and bathroom vanities.
What is Slate?
A slate originates as sediment, usually a fine-grained mudstone. Through the action of burial, compression and heat a mudstone will develop progressively from shale, and then to a slate. The definitive characteristic of slate is it's slatey cleavage, which enables the material to be split into parallel sheets. Certain English green slates originated as volcanic ash deposits that were deposited in water. As a roofing material, slate should last well over 100 years. It is suitable for flooring, fireplaces and walling. It can be flamed and honed. It is the most durable of natural stones in extreme atmospheric conditions. Used for swimming pool surrounds, flooring, and bathroom shower installations.
What is Travertine?
Travertine is a natural stone material from the limestone family. It is made of calcium carbonate and is usually found in the form of deposits near warm or hot springs were frequently used in ancient times as a building material. Because travertine is such a porous material, it should be sealed before use in construction or renovation projects. It is most commonly used for countertops and flooring, but may also be used in showers and tub surrounds as well as in exterior decor.
One might think that since stone can withstand the ravages of weather and outdoor elements, it is unlikely to be damaged when used in the home. Aside from its obvious beauty, durability is one of the elements that lead people to choose natural stone for home building and home improvement projects. Travertine is susceptible to heat, scratching, staining and acidity, including citric acid, so it should only be cleaned with special products designed for use on natural stone.
What is Onyx?
Onyx is a semiprecious stone that can often be found in fine jewlry and ornaments. Its refined beauty and elegance has made it the ultimate luxurious building material. Noted for its unique translucent quality, onyx is often used in illuminated applications.
from : http://www.allnaturalstone.com/stone_geology.html