Glossary of Natural Stone Terms

For definitions of other terms not listed here, please go to these sections: How It’s Made, Styles, Before You Buy and Before Installation.

Acid-Washed Finish
Marble and limestone are the most popular stones to be acid-washed, but most stones can hold an acid-washed finish. An acid-washed finish will give you a shiny floor that will hardly show scratches, but there are pits in the surface of the acid-wash finish. It is a rustic finish, that is considered more rustic than a honed finish.

Brushed Finish
As the name implies, a brushed finish is accomplished by brushing a stone to give it the impression of being worn down over time.

Bull Nose Edge
Polished Bull Nose Edge is an edge for a tiled natural stone floor that is rounded, or curved. A Straight 90 Degree Edge has straight lines. Even if the fabricating company does not provide Bull Nose Edges, Century tile can make the pieces for you if the stones are of the right quality – a harder stone will take to the process easier than a softer stone.

Calibrated
A stone slab is calibrated to create a uniform thickness that is the length of the slab. This is important to achieve a well-laid stone floor.

CBU
CBU is the abbreviation for Cement Backer Unit. A CBU is used on wood subfloors and provides support as well as a moisture barrier.

Ditra
Ditra is an underlayment that also acts as a protector. Ditra provides a waterproof barrier and allows for slight movement of the substrate.

Epoxy Grout
A type of grout with stain resistant properties usually used on food areas. Epoxy is always highly recommended.

Fabricator
Slabs are customized at a fabricator or factory to adhere to the requirements of specific installations.

Flamed Finish
A flamed finish is typically used on granite for areas requiring a slip-resistance, such as a shower. A flame finish gives the stone a rough texture by heating the surface to an extreme hot temperature, then rapidly cooling the stone. The surface of the stone chips due to the heat process, and this leaves the chipped texture which provides the slip-resistant qualities.

Granite
Granite is a hard, dense stone with scratch-resistant qualities that make it perfect for flooring and in food preparation areas. Granite is an igneous stone, resistant to acid-etching, and is found in many parts of the world. Several types of granite exist.

Honed Finish
A honed finish requires little maintenance and shows few scratches. It will give a stone floor a softer look, and can create a flat, matte or satin finish. This finish is created by actually stopping short before finishing the standard polishing process.

Igneous Rock
A liquid rock that comes from lava (in volcanoes) or magma (under the earth) and cools and hardens when it is exposed. Granite is an igneous rock formed from magma, and pumice is formed from lava.

Limestone
Limestone is a sedimentary stone, formed by sediments such as sand, shells, stones, and plant and animal remains collecting over hundreds of years. It comes in many earthy colors.

Manufactured Stone / Agglomerate Stone
Agglomerate stone is a manufactured stone that is four times stronger than granite. This gives it a greater protection against cracking and chipping. Natural stone chips are coupled with a strong binder, typically cement, epoxy, resins or polyester. Many agglomerates are made primarily from quartz. The quartz gives the stone strength, consistency, depth and radiance. Terrazzo is a popular agglomerate stone.

Marble
Marble is a metamorphic stone created by applying heat and pressure to limestone. It can be polished, but it does not resist scratching well, and is easily etched by acids. Marble stones can differ between continents.

Metamorphic Rock
When heat and pressure are applied to a stone, it is referred to as a metamorphic rock. Quartz, marble and slate are metamorphic rocks.

Polished Surface Finish
A mirror-like glossy shine enhanced by the stone's crystals. A polished surface finish is performed by polishing a stone with a polishing brush in the same manner as sandpaper would sand hardwood furniture. A finer polish head creates a glossier polish.

Porosity
Porosity refers to how porous a stone is based on the number of pores and amount of pores in a stone. Mathematically, it could be the absorption rate of liquids. Travertine is porous and has a high porosity rate, whereas granite is very dense and has a low porosity rate.

Quarry
Massive rock deposits formed from metamorphic rock that have protruded the earth's surface into what we now refer to as “quarries.” Where natural stone is often mined from. Sedimentary and Igneous rocks can turn into metamorphic rock, thus quarries will hold granite, limestone, slate, marble and travertine.

Sandstone
There are many varieties of sandstone available, however it is simply a rough sedimentary stone that is primarily made up of quartz and sand grains.

Saw-Cut Refined Finish
Stones are processed to remove the heaviest saw marks, but not all. This results in a matte finish, but not a honed finish. Granite, marble and limestone can be ordered with a saw-cut refined finish on special order.

Sealers
Sealers protect your stones and can retain the natural look of the stone. Required for stone floor installations.

Sedimentary Rock
Limestone, shale and sandstone are sedimentary rocks. Sediments such as mud, minerals and plant decay accumulate in layers over years and eventually form into a stone.

Slab
A stone that has been cut from a block of stone.

Slate
A layered metamorphic stone made up of shale, clay and quartz. It comes in many colors. Red and green are common.

Split Faced Finish
A split-faced finish is most often used for slate rock. It gives a rough texture, but not as harsh as a flamed finish. A split-faced finish is completed by exposing the natural cleft of the stone. This is done at the quarry using hand-cutting and chiseling methods.

Stone Tile
Stone tile can be custom made, but manufactured tiles are usually 12”x12”, 13”x13”, 16”x16” or 18”x18. Marble mosaics, medallions and feature strips are also manufactured in many different sizes.

Straight 90-Degree Edge
An edging with straight lines, not curved. Used where a crisp, modern look is required. A Bull-Nose Edge is curved.

Substrate
Stone tile is laid on a substrate. A substrate may be a subfloor, or it may be a layer on a subfloor. It's what the tiles are placed over.

Thinset
A method of adhering tiles into place. In a thinset method, a cement adhesive is troweled on a substrate and the tiles are placed firmly into the mortar. The amount of mortar can be adjusted to achieve a uniform look. The type of adhesive depends on the stone. We are more than happy to help you with your selection.

Travertine
A stone that can be filled and honed. Its density is similar in nature to that of marble. Travertine is made from crystallized metamorphosed limestone.

Tumbled Finish
Marble and limestone take well to a tumbled finish. A tumbled finish can give a floor a smooth surface, or a slightly pitted surface. Broken rounded edges and corners are characteristic. The look is achieved by putting tiles, typically 3/8” thick, into a machine to tumble. Sometimes 3cm tiles are tumbled, then separated so that each tile is tumbled on one side.

Unsanded Grout
Used when installing a natural stone floor to fill small joints. Sanded grout will scratch soft stones, but unsanded grout will not. Unsanded grout is a cement-based product that is mixed with water at the site of the installation. Excess grout is removed with a sponge. The grout must dry before walking on the floor.