Tile Selection Guide
There are more than eight thousand types of marble in the world today, and the number continues to grow. It would be impossible to list every type available, but there are some common characteristics that easily identify marble.
For those of you with a scientific curiosity, marble is defined as any limestone that will take a polish. Limestone, and, therefore, marbles are composed of minerals of calcite or dolomite. Marble in its purest state is white. Colored marbles are the result of other minerals mixed with the calcite or dolomite.
Now, for those of you who don't really care about that of which marble is made, there are some common recognizable characteristics. Marble, no matter what color, will usually have some type of veining running through it. The veins are usually different in color than the main color of the stone. There are, however, exceptions to the rule. Some marbles, such as Thassos White, will have little to no veining. Marble is relatively soft, when compared to other stones such as granite. It will scratch very easily. If you run a knife blade lightly across the surface of the stone, and it leaves a scratch, you may have marble. On dark marbles, these scratches will appear as light lines on the surface of the stone. On lighter colored marble, detecting a scratch may be more difficult. Marble is also very sensitive to acidic chemicals. Vinegar is acidic, and will leave a dull spot on marble. Avoid the following acidic materials: vinegar, lemon, tomato and tomato sauce, bleach, coffee, fruit juices, wine, urine, vomit, tile cleaners (like Tile X), mildew removers, X-14, acidic toilet bowl cleaners, cleaners with lemon, pool Ph. decreaser (Muziatic acid), and driveway cleaners. Most products that contain acids will have their ingredients listed on the bottle label. Avoid using them on, or near, any marble surface.
Like marble, granite is also a natural stone with many colors available; however, the similarities stop here. Unlike marble, granite is composed of different minerals with different properties. Granite is chiefly composed of 30% Quartz and 60% Feldspar. These minerals are much harder than the calcite of marbles, and, for this reason, granite will not scratch as easily as marble. Granite is very resistant to most acids, and will not etch, nor leave a dull spot, like it does on marble. The only acid to avoid is Hydrofluoric acid, which is found in most rust removers. Granite rarely has the veining characteristic of marble. Granite contains crystals, which are very distinct appearing to be small to medium stones compacted together. There are some exceptions. Blue Azul will have a vein like pattern, but if looked at closely this vein will also have small, distinct crystals. Granite is an excellent choice for countertops, especially in the kitchen, where it will be exposed to acidic foods and chemicals.
I'll try to make this as clear as possible. Limestone is not marble, but marble is limestone. Let me clarify. Limestone is made of calcite from shells, coral, and other debris. It is sedimentary rock formed by the breakdown of other rocks or shells, etc. Marble is a limestone that has been subjected to great heat and pressure that changes (metamorphosis) to marble. So you ask, "What's the difference?" There is a considerable difference. Limestone is usually loosely held together, and may differ in porosity from marble. The course grains in limestone give them excellent wear ability. Limestone can have numerous fossil impressions that are well preserved. If a slab of stone has various shell or animal-like patterns, there is a good likelihood it is limestone. To identify limestone, look for fossil-like impressions, and loose grain structure. Limestone comes in various colors, but most are shades of brown, or tan, and some lean toward red. All seem to fall into the earth-tone color range. Limestone is becoming increasingly popular in the West and Southwest.
Slate is a stone. It is commonly gray in color, but you may find green, yellow, and red hues. It is a material from metamorphosed shale; that is, it consists of clay-like materials, which have undergone change with exposure to heat and pressure. For the layman, slate can be recognized by its sheet-like structure. The material is usually thin, and, if broken in half, will flake off into sheets. Slate is rarely highly reflective, unless a coating is placed on top of it. Its surface is usually uneven, unless machine sanded.
Quartzite is a rare material used for flooring. Like limestone, it is gaining in popularity. It can be found in colors from white to a pinkish-brown. It is composed of metamorphosed quartz sand, or sandstone. It is acid resistant. Its texture appears sugary. It is commonly used on floors, patios, and driveways, etc.
Sandstone is a very rare flooring material. It commonly is used for building stone, but occasionally makes its way indoor as a flooring surface. Composed primarily of quartz, it is loose and rough in texture. As its name implies, it appears as sand cemented together. It is also acid resistant, and rarely is polished.
Agglomerate stones are composed of broken pieces of marble, and sometimes granite, cemented together, with a polyester or epoxy bonding material. Their properties are similar to the marble, or granite, from which they are made. Their plastic binders may appear less shiny, giving the stone an alligator skin-like appearance. Agglomerates are very popular, and inexpensive, compared to other natural stone. The refinishing requirements are slightly different due to the plastic binders.
Terrazzo flooring was very popular in the late 1950's, and 1960's. It is making a big comeback in the '90's. Terrazzo is a poured floor similar to cement, with the addition of sized marble chips. The marble chip and cement mixture is poured and spread out. The final product is achieved after grinding it flat, and applying a wax coating. The maintenance requirements for terrazzo are identical to that of marble. Terrazzo is also available as a tile.
COQUINA OR SHELL STONE
Coquina or SHELL STONE is a limestone consisting of broken fragments of shells and corals. Sometimes it may be called coral stone. It is a sedimentary rock, and is extremely porous. It wears relatively well, and is rarely polished.
Onyx is a type of marble, which has been deposited from cold solutions. It is characteristically translucent, with many veins running concentric to one another. It is very expensive, and usually found as a small tabletop. Its properties are similar to marble.
Travertine is a type of limestone, but differs, in that it is formed in hot springs called karst. The water movement in this karst erodes the travertine creating holes in the stone. Polished travertine will usually have these holes filled with colored Portland cement. These fillers typically are not polished, and will give the travertine a blotchy appearance. Unfilled travertine will exhibit these holes, and are commonly found on walls, floors, and building exteriors. Travertine is commonly found in tans and beige colors, but can also be found in silver and reds.
Concrete tile is available in various sizes, and an endless variety of colors. It can be painted to simulate natural stone, and is often mistaken for the real thing. These tiles are an excellent substitute for natural stone for those on a tighter budget. Care must be taken in selection, since many poor grade concrete tiles will wear and discolor faster, and easier, than most natural stones.
MEXICAN TILE/TERRA COTTA
Mexican tile is a terra cotta type material. Terra cotta is made from clay, which is baked in the sun, or oven dried. Color range is limited to browns, yellows, and reds. Some terra cotta can be stained, or pickled, with dyes to change its color. These dyes easily wear. Mexican tiles are typically unglazed, but there are glazed tiles available.
Ceramic tiles are made from a mixture of clays baked at very high temperatures. From small one-inch mosaics to large eighteen-inch square floor tiles, the size and color of ceramics are limitless.
Ceramic tiles are available in glazed or unglazed finishes. A glazed finish is a hard surface, usually glossy or satin-like, but can be matte, semi-matte, or dull. Glazing is achieved during the baking process by applying a special material called a bisque, after which a second occurs. The color and patterns in most glazed ceramic tile is in this glazed layer. When you chip a ceramic tile, you remove this glazed surface.
Unglazed ceramic tile contains no glaze. It is usually dull and is die color of the clay used to make the tile. Unglazed ceramic tiles that have a sheen or gloss, have a sealer or wax treatment applied to them.
Quarry tile is an unglazed ceramic tile. It is commonly found in commercial kitchens and restaurants. The surface is rough, and available in earth-tone colors. They are excellent tile for areas where slip resistance is a concern.
Porcelain tile is becoming increasingly popular as a durable floor tile. Like ceramic tile, porcelain is baked. Unlike glazed ceramic, porcelain does not have a bisque surface. The material is consistent throughout the tile. It is almost impossible to chip, and is nearly indestructible. Light-colored porcelain can trap dirt, requiring regular maintenance. Porcelain is available in tiles as large as two foot square. It comes in a honed or polished finish.
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