Whether you're designing your own kitchen or a luxurious business centre, you might think of adding to it natural stone elements. These can be a granite worktop, onyx reception desk, travertine floor, marble wall. The choice of natural stone colours and patterns is immense, there's a stone to match every interior and any space. Comparing the properties of different natural stones will help you decide which one suits your project best.
Each natural stone has its own distinct character, it's like a living personality in your home. Quiet, mysterious, mature - these are the words to describe any type of stone. However, these versatile stone qualities usually are complemented by some distinctive features that make one specimen stand out among the others. Have you noticed that marble has cool and classic looks when compared to sensitive and extravagant onyx? Travertine is shy. Its modest personality often tends to pass unnoticed, but at a closer look it reveals small, playful holes.
Different rocks found in nature tell their unique stories that are millions of years old. Isn't it wonderful that looking at your natural stone wall or fireplace you will be able to read those magic sagas? Just think: as you slice bread or stir your soup on your new kitchen countertop, you can watch the journey of the stone unfold before your eyes. The endless cycles of erosion, sedimentation, sinking and uplifting are reflected in the veins and fractures of the stones.
The most common natural stone used by interior designers in their projects is marble. When looking at soft marble colours and its subtle veining, it's easy to guess why. Light marble surfaces complement to interiors' air and elegance, while dark marble patterns add to conservative and classic looks.
Granite and quartzite stand out among other decorative stones in terms of their hardness and durability. Both of them can surprise by bold colours and patterns. Pure quartzite rock is harder than granite. It is composed almost entirely of quartz particles. Generally quartzite tends to be white, but due to accidentally trapped minerals it can acquire fabulous colours and patterns. The charms of quartzite are hard to resist.
Because of its translucency, the extravagant onyx makes itself highly noticeable in any interior. Onyx walls and partitions, when illuminated from the opposite side, create a real drama. Agate, aragonite and amethyst walls also glow when backlit, turning themselves into natural masterpieces. Some exotic stones that are not translucent, such as jasper, lazurite and amazonite, also add to interiors' lavish and luxurious looks.
Have you thought that a sandstone countertop can teleport you to the sand dunes while you are sipping coffee in your kitchen every morning? Sandstone patterns in shades of yellow, orange, greyish amazingly resemble dunes. Travertine is more modest than sandstone, but it also boasts a special earthy texture. Because of its neutral look travertine fits almost anywhere. Its distinct feature are playful natural holes, which can either be left open or sealed with transparent sealants by worktop manufacturers.
Grey and black basalt has more reserved looks when compared to many other stones. It is less common in interiors though it has some excellent characteristics. The basaltic rock which forms the ocean floor is environment-friendly, non-toxic and non-flammable. Basalt is ideal for outdoor use as it can withstand severe temperature fluctuations and extreme weather conditions. Strong and gallant basalt slabs are great heat retainers, their thermal insulation performance exceeds that of other stones.
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Different stones used in interior and exterior decoration are found as rocks in large solid chunks in the ground. They are transported from quarries in large blocks. Before being shipped, the blocks are cut into slabs of approx. 3.2 m long and 1.60 m wide, 2-4 cm thick. Natural stone slabs of incredible beauty arrive in Lithuanian stone fabricators warehouses from all over the world.
Natural conditions in different parts of the world lead to different minerals forming in the ground. This also explains the different composition, properties, textures and appearance of the same type of rocks that formed in different places. All these parametres in decorative stones can vary considerably.
Most white marbles come from Italy. Some beautiful coloured marbles come from South America, Asia and Africa. Extravagant green and black granite slabs with veiny textures come from Brazil. The lands of ancient Egypt, Babylonia and Assyria were famous for exotic precious and semi-precious stones. Many gemstone slabs are still coming from the Middle East today.
According to the famous Lithuanian geologist Vincentas Korkutis, rocks appear to be unchanging only at first glance. Given the right conditions, they can change beyond recognition. The rocks are constantly forming and transforming under ground. Nature's imagination has plenty of resources to run wild as there are more than 3,000 types of minerals beneath the earth.
Around 1/6 of the Earth's minerals (about 500) are found in larger quantities in the ground. They form the bases of the most common rocks. The rare ones are added to the base ones by nature as condiments to foods. The physical properties of the stones used in interiors and construction mainly depend on the atomic size and valency of the minerals they contain. Among the minerals in the Earth's crust, quartz, mica, feldspar, amphibole and pyroxenes are the most abundant. When quartz is broken down into the finest grains it becomes sand.
Rocks can be simple and complex. Simple rocks consist of a single type of mineral. For example, marble and limestone are composed of calcite grains. Complex rocks consist of several types of minerals. Such complex type of rock is granite (Latin for 'granular'). The component parts of granite have different grains. Even without magnifiying glass it is easy to distinguish clear irregular quartz grains, mica plates, brownish or grey feldspar crystals.
The rocks found on the Earth's surface have been formed by physical and chemical processes. They are classified according to their origin as igneous, metamorphic and sedimentary. If your worktop is made of igneous rock, such as granite or basalt, it means that this material was either spat out of the earth's interior as liquid magma, or it was trapped in the earth's crust and cooled before reaching the surface.
If your worktop is fabricated from a sedimentary rock, such a travertine, it means that it formed at the surface of the earth from crystallised mineral deposits. If the origin of your countertop stone is metamorphic, it means that it has gone through a hell of heat and pressure in the earth's depths, transforming from one type of rock to another. Such stone is Marble.
Most rock formations are formed in the depths of the earth and gradually rise to the surface through physical processes. The deeper the rocks sink, the higher the temperature and the higher the pressure. Lava erupting from the depth of 100 km reaches temperatures of 1200-1500 degrees Celsius. At these depths, rocks are subject to pressures of tens of thousands of atmospheres. Geologist Vincentas Korkutis, in his book "The World of Minerals", explains how these conditions produce minerals of astonishing beauty.
The Earth's depths are filled with magma, which is a viscous silicate mass made of silicon and oxygen and rich in dissolved chemical elements. Hot magma rises upwards under the influence of underground forces. If it solidifies before reaching the surface, intrusive rocks are formed. This means that hot silica compounds trapped in veins, cracks and fissures of earth penetrate through them into other rocks. Silicon compounds are abundant, they make up two-thirds of the Earth's crust. Silicon and aluminium compounds are present in feldspar, mica and other silicates. The composition of the newly formed rocks depends on the temperature and pressure at a given depth.
Magma erupting freely through fissures to the surface forms effusive rocks by rapid solidification. The elements in it don't have enough time to crystallise because the mass of magma solidifies too quickly. Effusive rocks include basalt, andesites and porphyrites, which are widely used as building materials. Such rocks form the Scandinavian mountains.
Closer to the surface, where the temperature and pressure is lower, rocks start to weather and etch. Fine mineral deposits in rivers, seas and oceans build up sedimentary layers of sand, clay, chalk and other residue. Over thousands and millions of years, as the Earth's crust moves, sedimentary rocks sink downwards. The deeper they go, the higher the temperature and the higher the pressure. As conditions change, new metamorphic rocks begin to form. This is how limestones become marbles and clays become shales.
Impurities give to the stones their different colours and shades. The varieties of the same mineral are often called by different names. For example, clear quartz is called rock crystal, purple quartz is called amethyst, yellow quartz is called citrine, smoky quartz is called morion, and greenish quartz is called prasiolite. One colour can often be seen to change imperceptibly into another. White, yellow, brown, red and black colours are painted on striped agates and other minerals of the quartz group - tiger's eyes, cat's eyes, falcon's eyes.
Transparency or translucency is the ability of stones to transmit light. It depends on their chemical composition, mineral structure and slab thickness. Minerals come in transparent, opaque and partly opaque forms. Transparent minerals include quartz, gypsum and Icelandic spatter. Some minerals are only translucent at the edges, such as emerald. Opaque minerals are most sulphides. Some minerals absorb light differently in different directions.
Some stones can be instantly recognised by specialists, while others can only be identified by laboratory tests. Sometimes it might be difficult to distinguish the type of stone just by looking at it. To the untrained eye, two stone slabs of similar colour might look identical, but in reality they can be different. For example, granite, marble and quartzite slabs can have almost identical patterns and colours. Even by touching, patting or knocking on them it can be hard to tell which is which.
The most important physical properties of stones are their hardness, structure, texture, scratchiness, weathering. These are called mechanical properties. Optical properties are stone transparency, colour, lustre. Morphological properties are the crystal appearance, faceting, density, magnetism, electroactivity, radioactivity. Surprisingly, colour is not the main characteristic of a stone. Sometimes a piece of stone that has been ground turns into dust of a completely different colour.
Some stones can be easily identified by their lustre, i.e. the amount of light reflected from their surface. Lustre is measured by the refractive index of light and can be diamond, glassy, oily, waxy, pearly, pearlescent and silky. Two-thirds of all minerals are glassy, in particular quartz, corundum and topaz, which have a refractive index of 1,3-1,9. Minerals with a higher refractive index (1.9-2.6) are more brilliant - e.g. zirconium, diamond. When the coefficient is even higher, the mineral has a metallic sheen. Chalcedony has a low lustre, while precious opal, mica and talc have a pearlescent lustre. The light falling on opal is reflected not only from the surface, but also from the inner planes of the scales. Malachite has a silky lustre.
Both natural stone and engineered stone surfaces look great in any interior. However, before choosing the right material for your project, there are some important things to consider. Mainly, where the item will be placed, how much its surface will come into contact with liquids, and how much time you will want to dedicate to its care and maintenance.
Granite, marble, travertine or any other natural stone is porous. This means that stones can absorb liquids, just like sponges. Some stones are more porous, others are less porous. Polishing the stone surface reduces its porosity, thus glossy surfaces will be less porous than untreated or honed surfaces. Even non-coloured liquids can change the colour of the stone and cause stains. To prevent this from happening, natural stones need special care.
To protect natural stone surfaces from staining, countertop fabricators recommend using sealers and waxes. They should be applied regularly, generally every 12-24 months, depending on the stone type. Each stone type has different porosity, and therefore requires different care. Artificial stone products have very low porosity or none at all, therefore they do not require sealing and generally require less care.
To seal stone surfaces, liquid sealants are commonly used. Once applied to the stone, sealers fill the pores and stay in them (get trapped). This makes the surface impermeable to water and grease. Some stone sealers are also colour enhancers. They not only protect stone surfaces from staining, but also give them brighter appearance.
To get the best results, it is recommended to use a pH neutral cleaner after the surface has been treated with the sealer. Acidic cleaners break down the sealer that is meant to help the stone resist staining caused by liquid substances. Acidic cleaners can stain marble, limestone, sandstone, travertine surfaces and make them etch. This is much less likely to happen with engineered stone.
One more thing: glossy natural stone surfaces are especially susceptible to getting their appearance marred by tiny scratches. When scratching happens continuously, the former glossy finish will start to look dull. Some engineered stone types are more resistant to scratching.