Natural stone is a geographical list of stones under the categories of igneous, metamorphic, and sedimentary rocks that exist without the influence of man. They are otherwise known as marble, limestone, granite, travertine, quartzite, and slate. These natural stones are either currently or historically quarried from many continents and nations across the world.

Most common U.S. homeowners are unaware that they are purchasing natural stone quarried overseas and often expect the same tile they got a sample of. However, the reality is the natural stone has natural color variations that make it appealing and unique just as nature intended.

The natural stones are most commonly used in building construction and sculpture monuments, as well as for decorative and aesthetic purposes such as stone engraving. With many options of stone and finish, you can create any custom cut or appearance you please.

Almost all natural stone tiles are imported into the United States. The only granite tile that is quarried in the U.S. is the Dakota Mahogany, which comes out of North Dakota.

• Granite and Slate tiles (most) come from Brazil and India,
• Marble tiles come from Italy, Spain, Turkey, Greece and China
• Limestone tiles come mainly from Israel, Egypt and Portugal
• Travertine tiles come from Turkey, Mexico and Peru.

The country of origin has an impact on the quality of tiles and some tiles are even named by the country of origin. For example, the travertine tiles that come out of Turkey are called "Tuscany", while the travertine tiles that come out of Mexico are referred to as "Durango".

The most common natural stones are:

• Marble
• Granite
• Travertine
• Limestone
• Slate
• Sandstone
• Quartzite

Marble is used commonly used as a building material and most noticeably, for sculpture. The stone is a non-foliated metamorphic rock composed of recrystallized carbonate materials. Most non-foliated rocks are produced by contact metamorphism; which is when heat from cooling magma modifies the structure of rock previously crystallized, resulting in its foliation becoming slightly visible.

Granite is commonly used as construction stone because it is a distinctly tough stone. Granite is a type of igneous rock with at least 20% quartz by volume, which is visibly crystalline in texture and formation. It is composed of feldspar, which gives granite that gray or flesh-color (pink-red) façade. Granite also crystallizes from magma that slowly cools, deep beneath the earth's surface. Interestingly, granite is one of the stones that serves as the foundation of our world's continents as we know them.

Travertine is a sedimentary rock and form of limestone formed by a rapid precipitation of calcium carbonate at the mouth of a limestone cave or hot spring. The porous nature of travertine is distinct as algae, bacteria, and other organisms colonize and absorb it. Italy has the most well-known travertine quarries in the world, which has includes historic value such as the famous St. Peter's Basilica, built by Michelangelo who made travertine his choice stone. Travertine is commonly used as a building material such as paving pathways and patios. There are natural holes in the stone, which is sometimes filled with grout, or sometimes left open depending on the preference of the customer. Since the stone is on the softer side of the spectrum, travertine can prove difficult to finish and maintain.

Limestone is a sedimentary rock composed mainly of naturally occurring calcium carbonate minerals. The rock is composed mostly of grains that come from skeletal fragments (shells) of marine organisms. Limestone is most commonly used in architecture as it is long-lasting and holds up to exposure of harsh conditions quite well. It's no surprise that the Great Pyramid in Egypt in addition to other complexes, were cut from Limestone. It is readily available easy to cut or carve, and is a solid material to use as the base of highly trafficked places like roads.

Slate is a homogenous metamorphic rock and that is largely composed of quartz and muscovite, formed from clay on ancient sea beds. It can be defined as a fine-grained rock derived from clay and shale that can be split into thin sheets. The most common uses for slate include roofing and flooring tile as slate can form smooth, flat sheets of stone. It has been used to for fireproofing structures and for building electric switchboards since it is a great electrical insulator. Depending where the slate is extracted, its colors can range from the most common gray, to greens and purples. If you happen to see a fossil in any of your tiles, you can accent the room so it can be seen easily.

Sandstone is a sedimentary rock that is formed from cemented grains of sand. The cementing material in sandstone can be made harder or softer depending upon the make-up of the cementing material, which adds flexibility to its use (i.e. adding more quartz makes sandstone harder). Sandstones mostly come in a range of earth tones such as red, brown, and green, but have been known to deviate in color. Sandstone is widely used in the construction industry due to its durability and sheer strength. It's commonly mixed in building and paving materials., Ironically, sandstone can also be crushed back into its fundamental state, back to sand, for other building and design-related projects. Sandstone is usually found in deserts like the vast Sahara Desert, old rivers, lakes, beach shores, Deltas, and similar dry environments where there was once a sea or body of water.

Quartzite is a form of sandstone that has gone through metamorphosis by heat and pressure, therefore making it a hard and non-foliated. Since it so rigid and sharp, it is very resistant to chemical weathering and serves as a great building material for railroad track ballasts and other road construction. It is also used decoratively to cover walls, as flooring, and for roofing tiles. Pure quartzite is typically gray or white, although shades of red, orange, and pink have been found due to elevated amounts of iron oxide and/or other impure minerals.

For a stone to take a high polish it must be a very dense stone that can handle its finish being ground until glossy. A polished stone has square corners and somewhat slanting edges that can be fitted together snugly with little grout needed between them. It can be used for any floor, wall, or countertop, but it is not recommended for areas prone to excessive moisture due to slipping danger (i.e. kitchen floor). The finish can lose its shine over time so upkeep is required. Crystallized stones like marble and granite take polish best.

similar to the polished stone, but does not come out glossy. Rather, grinding and sanding produces a smooth, flat finish known as matte. This is great for low maintenance, high traffic projects. Honed stone tiles give an application a more modern feel that is sleek and more refined. The colors of honed stone tiles are duller than the polished tiles, creating a less formal look. Non-crystallized stones like limestone and travertine hone best.

The opposite of polished, tumbled stone creates a rustic, old world look that is timeless. The stones are literally tumbled in a blend of sand, water and mild acid that creates a weathered appearance. Typically, tumbled stone tiles are also ground down on their back in order for a smoother installation. Must be installed by a wide grout joint due to uneven edges.

has a rough and uneven surface that works great for flooring, exterior applications, or wet surfaces since its surface provides for better grip. Cleft stone tiles are split, instead of cut with a saw, and would be a terrible choice for a countertop application.

A type of honed finish cut with use of a Diamond-toothed Saw, a stone block is sawn into slabs, cleaned, and left smooth. It is somewhat reflective, but not close to a glossy, polished finish. You can use a diamond sawn finish on any stone.

A rough sawn finish, which is a natural stone in its "rough" state, can give any project a rustic, natural feel. The tile is uneven and works well for flooring outdoor or indoor applications.

This finish is a rough, patterned surface with the use of different abrasive power-tools such as the bush hammer itself. Semi-abrasive for slip-resistance, therefore a good choice for surfaces that see heavy foot traffic. This finish can be applied to any material with a minimum thickness of 3" (2cm).

use of an abrasive material delivered by a sandblaster can give natural stone a bumpy, rough surface if originally smooth, and a smooth surface if originally rough. Sandblasting is used in stone engravings in most modern cemeteries, art, to refurbish buildings, and for various cleaning applications.

literally impacting a stone with a hammer and chisel, therefore the tile is usually very thick. Any stone can be chiseled and the resulting surface (ranging from either very rough to only slightly rough) is reliant upon the skill of the person and the type of chisel being used. This finish leaves uneven edges and an uneven surface, which gives any project an antique feel.

use of intense heat flaming treatment leaving a coarse surface with little reflective qualities. The color of the stone treated can actually change depending on varying levels of minerals (i.e. Iron) within each stone

• Most natural stones come in 12x12, 16x16, 18x18 and 24x24 sizes. Some special order or "field size" natural stone projects might use 36x36 tiles as well. Besides the field tile sizes, there are many mosaic sizes such as 5/8x5/8, 1x1, 2x2, 1x2, 3x6, 4x4, 6x6 and 6x12. The 3"x6" tile size is also referred to as "subway tiles".
• The smaller mosaics like 1x1, 1x2 and 2x2 are installed on a 12"x12" mesh-backing to make the installation easier and so that the small sizes don't fall apart. Any size over 3x6 or 4x4 are installed individually.
• Slab sizes vary from 104"x70" to 125"x80". Smaller sizes are available too.
• Slates and Quartzites are produced in nominal, and not exact sizes. i.e. A 12" square tile may actually measure 11.87" square.

• Standard thickness for 12x12 tiles is 3/8", 1" for 18x18 and 3" for 24x24 tiles.
• The reason why the stone gets thicker as it gets larger is because the natural stones are brittle and the only way to ensure undamaged transportation & installation of larger stones is to supply thicker stones that can withstand the unpredictable conditions along the way.
• Standard thickness for 16"-24" square tiles varies from 0.5" - 0.75"

Example: The thickness of a kitchen countertop is generally either 0.75" or 1.25". In the eastern U.S. the thicker is preferred, while western consumers prefer the thinner.

Natural stone vs Man-made tiles (made of Ceramic/Porcelain)

• Ceramic/porcelain tile is a man-made product and natural stone is extracted from the earth.
• Natural stone differs in color and no two pieces ever look the same. They are unique.
• Many ceramic/porcelain tiles are made to imitate some type of stone. They are more controlled in range and deviation, however many people have trouble distinguishing between natural stone and ceramic/porcelain tile due to the improved technology used in modern day.
• Natural stone requires long-term maintenance vs. ceramic/porcelain, which requires no extended upkeep and is virtually maintenance-free.

Comparisons of Porcelain/Ceramic tiles with Natural Stone