A guide to understanding the origin of stone floor tiles and their characteristics.
Basic ingredients of igneous stone
The four basic elements of rocks are silicon, magnesium, iron and calcium. Rocks with a large portion of silicon tend to be lighter in colour and may even appear transparent. Examples are granite, quartz and onyx. Rocks that contain low amounts of silicon are called Ultramafic and tend to be darker and opaque due to its high magnesium and iron content. Examples are peridotite and chromite.
Igneous rock is formed when magma cools within the earth (intrusive) or above the surface (extrusive). Intrusive solidification is slow due to the warm earth keeping the mixture in liquid form, and combined with the earth’s pressure these two conditions assist in the formation of crystals, which are similar elements that attract each other during the liquid state. The pressure of the earth above also forces low-density particles to the surface, leaving densely-compacted rock around the crystals. Examples of intrusive igneous rock are granite, quartz, peridotite and chromite.
The extrusive solidification process forms rocks with lower density because of the lower pressure and temperature above the earth. The external pressure does not force out the light-weight compounds, such as air, and because the temperature is colder it solidifies much quicker. Examples are pumice, rhyolite, obsidian and basalt.
Although some igneous rock can contain calcium, the majority of calcium-rich rock is formed as sedimentary rock above the earth’s crust. This lightly compacted rock is often formed of layers and contains remnants of dead plants and animals along with compacted particles of eroded igneous rock. Examples are flaky shale, sandstone, limestone, travertine and onyx. The latter two are formed as stalactites and stalagmites in cave interiors.
When exposed to high heat and pressure, igneous and sedimentary rock can both become compressed into various types of metamorphic rock, as shown in the picture.
Popular stone tiles
The most popular stone floor tiles that we’ve encountered in homes and offices are granite, limestone, travertine, sandstone, slate and marble. These stone tiles are also found on walls and countertops, however the most opulent stone panels of all are made of quartz and onyx, which are slightly translucent and look so beautiful with a backlight. These large Quartz and Onyx crystals are retrieved from larger rocks and glued together to form one magnificent panel of uniform colour.
Stone tile surface and textures
When stone tiles are shaped by the factory the surface can be produced as gloss, honed, tumbled or brushed. These textures are created through sanding and agitation with rotating abrasive blocks that are made of stone, silica-carbide brushes, or hard resin blocks that’s been combined with tough diamond-like particles.
Gloss has a reflection meter reading of around 100. At this point the clarity of the reflection is at its highest and is usually achieved with polishing powder.
A honed surface has a gloss-meter reading of up to 60, which is a matt surface, and depending on the stone content each type of stone can offer a different degree of shine. This is usually a feint reflection when looking across the floor into the sunlight.
A tumbled tile usually has an aged uneven look along the edges and the grout lines between the tiles tend to be wider. The surface is often honed and the natural imperfections of the stone is more visible due to a slightly rough agitation process that ages the surface.
A brushed tile has a rougher surface than a tumbled tile and often has a dry and powdery surface that can be beautifully nourished with a colour enhancer sealer. Slate and dark limestone look really lovely with colour enhancer (4th picture).