Abrasive hardness (Ha) is an industry method to determine the ability of a particular stone’s resistence to wearing from abrasive substances. This can be an important consideration when selecting stone for flooring in a commercial setting. It is generally recommended that stone being considered for flooring have a Ha of 10 or more, or even 12 or more in heavy traffic areas. It is also recommended that if different types and varieties of stone are used together that the Ha ratings should not be too far apart from each other. This will ensure a uniform appearance when the stone begins to show wear.The dirt and grit that is tracked into buildings has a hardness range from 3 to 7, and foot traffic tends to have an abrasion factor of 120 to 220 grit – equivalent to sandpaper at the same grits.

Absorbency is an important determining factor in stone’s sensitivity to stains. The size of the pores, their orientation, how well they are networked and the type of finish the stone has are important contributing factors to a stone’s overall absorbency.

In relation to cleaning ability this factor is more important than how porous a stone or tile is. Honed and textured surfaces are more susceptible to soiling and staining due to the fact that there are more open pores at the surface than a highly polished finish. The polishing process has a tendency to close off pores leaver fewer exposed, resulting in a low absorbent surface. However, some varieties of stone have large pores and capillary structures and even when these stones are polished they still remain very absorbent.

A man-made mix of natural stones (such as pieces or chips of marble, granite, and so so) mixed in with either a concrete or resin base.

Materials made of non-metallic minerals that have been permanently hardened by firing at a high temperature, or objects made of such materials. Most ceramics resist heat and chemicals and are poor conductors of heat and electricity. Traditional ceramics are made of clay and other natural occurring materials, while modern high-tech ceramics use silicon carbide, alumina, and other specially purified or synthetic raw materials. The oldest known fired ceramics date from the Palaeolithic period some 27,000 years ago.

The chemical composition of a substance refers to the elements of which the substance is composed. For example, marble is composed of calcium carbonate (CaCO2), plus any of a range of other minerals that are responsible for giving marble its colour. Stone and tile is made from different substances, whether naturally or through an engineered process, and the chemical composition determines its behaviours and how it can be treated.

A man-made mix of natural stones (such as pieces or chips of marble, granite, and so so) mixed in with either a concrete or resin base.

A structural masonry material made by mixing broken stone or gravel with sand, cement, and water and allowing the mixture to harden into a solid mass. The cement is the chemically active element, or matrix; the sand and stone are the inert elements, or aggregate. Concrete is adaptable to widely varied structural needs, is available practically anywhere, and is fire resistant. However it is not water resistent – in fact it is very porous.There are now a number of designer concretes available, which take this traditional material and add some style to it, usually in the form of colour.

A man-made mix of natural stones (such as pieces or chips of marble, granite, and so so) mixed in with either a concrete or resin base.

A naturally-made stone whereby fossils have been embedded into the stone as it has formed.

Coarse-grained igneous rock of even texture and light colour, composed chiefly of quartz and feldspars. It usually contains small quantities of mica or hornblende, and minor accessory minerals may be present. Depending on the feldspar present, granite may be pink, dark gray, or light gray. It is commonly believed to have solidified from molten rock (called magma) under pressure. However, some granites show no contacts with surrounding wall rock, but instead gradually grade into metamorphic rock. Others show relic features found in sediments. This evidence suggests that some granites are not igneous in origin, but metamorphic. Some granites are the oldest known rocks on earth; others were formed during younger geologic periods. Crystallized at depth, granite masses are exposed at the earth's surface by crustal movement or by the erosion of overlying rocks. Very coarse-grained granite, called pegmatite, may contain minerals and gemstones of economic value.

Hardness and density in relation to stone surfaces is a measure of the resistence of any substance that will scratch or abrade its surface. The hardness factor is a physical property of the stone’s mineral composition, density and porosity. Different minerals and stones have different degrees of hardness and density and therefore have different degrees of resistence to scratching and abrasion.

Refer to MOH scale of hardness for measurements of hardness and density.

A type of sandstone found only in New Zealand.

Metamorphic rock composed wholly or in large part of calcite or dolomite crystals, the crystalline texture being the result of metamorphism of limestone by heat and pressure. The term marble is loosely applied to any limestone or dolomite that takes a good polish and is otherwise suitable as a building stone or ornamental stone. Marbles range in colour from snow-white to gray and black, many varieties being some shade of red, yellow, pink, green, or buff; the colours, which are caused by the presence of impurities (other minerals within the calcium carbonate structure of the marble), are frequently arranged in bands or patches and add to the beauty of the stone when it is cut and polished.

The MOH scale of hardness is the method used to measure the ability of one substance to scratch another. The scale ranges in order of increasing relative hardness from 1 (softest) to 10 (hardest).

The objective of the MOH scale is to measure stone’s resistence to hardness. The harder the stone, the more resistent it is to abrasion. When sediment and grit are harder than the surface, they will scratch and harm the stone. Exterior sediment that is tracked into buildings measures between 3.0 – 7.0.

The art of arranging colour pieces of tile (or other materials) to produce a surface ornament.

Associated with stone’s porosity is permeability. This is the extent to which the pores and capillary structures are interconnected throughout the stone. These networks, their size, structure and orientation affect the degree and depth to which moisture, vapours and liquids can be absorbed into the interior of the stone or migrate from the substrate by capillary action through the stone. Permeability may be greater in some directions than others based upon the pore size, shape and the distribution of the interconnectedness of the system.Permeability is increased when a stone is highly fractured or the veining material is soft or grainy. A particular variety of stone may be highly permeable (a well defined interconnected network of pores), although its porosity is low (a low percentage of voids).The size and shape of pores and the capillary structure differs in stones and is an important factor in relation to stone decay.

A hard, permanent, nonporous pottery, which is sometimes translucent, and which is resonant when struck. Porcelain was first made by the Chinese to withstand the great heat generated in certain parts of their kilns. The two natural substances used were kaolin, also known as china clay, a white clay free of impurities that melts only at very high temperature, and a feldspar mineral called petuntse that forms a glassy cement, binding the vessel permanently. The current definition of porcelain in terms of tiles is a tile that is made containing a certain amount of white China clay, however there is no set guideline of the amount to be used so the term can be used loosely.

Porosity is by definition the ratio of voids to solids in a tile. It is measured by the amount of water a tile can hold, expressed as a percentage of it’s own weight. The test is carried out by firstly weighing a dry piece of tile, soaking it for 24 hours in water, drying off the surface water, and then weighing the wet piece. The tile’s porosity measurement is the percentage difference between the dry and the wet weights.

Sedimentary rock formed by the cementing together of grains of sand. The usual cementing material in sandstone is calcium carbonate, iron oxides, or silica, and the hardness of sandstone varies according to the character of the cementing material; quartz sandstones cemented with quartz are the hardest. Sandstones are commonly gray, buff, red, or brown although green and some other colors are also found. Green sandstones often contain, in addition to sand and glauconite, fossil shells and iron oxides; those that break apart easily are known as greensands and are sometimes used to replenish depleted potash in soils. Sandstones are widely used in construction and industry.

A naturally-made stone whereby shells have been embedded into the stone as it has formed.

Fine-grained rock formed when sedimentary rocks such as shale are metamorphosed by great pressure. Slate splits into perfectly cleaved, broad thin layers; this characteristically regular and planar cleavage is called slaty cleavage. In the formation of slate, pressure causes the flaky minerals within the sedimentary rock, such as mica, clay, and chlorite, to be reoriented; the flat faces of the minerals lie at right angles to the source of the pressure, and the planes of easy cleavage are also at right angles to the source of the pressure. The rock is not necessarily compressed in the same direction as the sedimentary layers were originally laid down, and because the compression crumples and deforms the original sedimentary layers, the planes of slaty cleavage usually cut through the old bedding planes. Slate is intermediate in hardness between mica schists and shale. Its characteristic color is gray-blue.

From the Italian word meaning baked earth, terracotta is a form of hard-baked pottery tile which is used either in its natural red-brown colour, or painted, or with a baked glaze. Terracotta has been used architecturally since the 7th Century BC.

In modern practice terracotta is manufactured from carefully selected clays, which, combined with water and vitrifying ingredients, are put through a pug mill or other device to reduce the mass to homogeneity. In cakes of convenient size the clay passes to the molding room. In the case of repetitive pieces such as tiles the clay is pressed into plaster molds to form a shell. The molded pieces are finished by hand and then are ready for baking in a kiln or reverberatory furnace.

A faux-marble flooring system, originally created by Venetian construction workers as a kind of 15th century value-added product. The workers used marble chips from upscale jobs to create Terrazzo. The workers would usually set them in clay to surface the patios around their living quarters. Consisting originally of marble chips, clay, goat milk (as the sealer), production of Terrazzo became much easier after the 1920s and the introduction of electric industrial grinders and other power equipment. Modern terrazzo is made with synthetic resins like epoxy or urethane.

A form of massive calcium carbonate, CaCO3, resulting from deposition by springs or rivers. It is often beautifully coloured and banded as a result of the presence of iron compounds or other (e.g., organic) impurities. This material is variously known as calc-sinter and calcareous tufa and (when used for decorative purposes) as onyx marble, Mexican onyx, and Egyptian or Oriental alabaster. Travertine is generally less coarse-grained and takes a higher polish than stalactite and stalagmite, which are similar in chemical composition and origin.