Stone

Here, we are going to expose you some little secret of Stone. So lets take a look on it....

History of Stone


Back to the ancient period, stone was clearly used in construction the Romans’ buildings and they were skilled in quarrying it. Additionally, they used different sort of stones in different types of applications such as marble would be clearly used to decorate surfaces of wall or floor and limestone would be used for pedestrian areas.

Figure 1: Earth Crust

In geological term, stone is actually known as rocks, and they have been used mostly in building and construction. Stone is formed to be a natural solid formation from many minerals. Throughout the centuries, there are thousands of types of stone have been quarried all around the world. The natural stone are mostly come from Spain, Mexico, Italy, Turkey, United States, India, Greece, Brazil, France and China.

Figure 2: Calcite Mineral

he minerals in the stone are similar the liquid and gas minerals that are formed in the earth. A massive body of gas and liquids has been developed in the earth, where they are slowly cooled and condensed into a solid core. Heavy minerals were forced down by pressure to the core of the Earth and the crust began to form. As the crust gets thicker and thicker, it squeezed around the inner core. In this situation, the crystals and other solid forms began to grow and form colossal rock beds. Nowadays, many rock beds are used as quarries where the stone is mined. All these minerals can be identified by their colours, hardness, and the formation of crystals.

Types of Stone

The most common types of stone that are used today, which are identified through four categories: SEDIMENTARY, METAMORPHIC, IGNEOUS STONE, and MAN-MADE. 

I) SEDIMENTARY stone is mostly come from organic elements such as glaciers, rivers, wind, oceans, and plants. Besides, tiny sedimentary pieces broke off from these elements and accumulated to form rock beds. They were formed and bonded together throughout millions of years of heat and pressure. For example, limestone, sandstone, soapstone, fossilstone, and travertine are the examples of sedimentary stone. 

Figure 3: Limestone

• Limestone mainly comprises calcite, which is also known to contain lime from sea water. This stone does not show much crystallise structure and it has a smooth granular surface. Some dense limestone can be polished and its colours are commonly black, grey, yellow, white or brown. It is more likely stain than marble. 
• Sandstone is a very durable formation of quartz grains (sand) and it is usually formed in light brown or red colours. In fact, it comprises silica, calcium, clay, and iron oxide. 
• Soapstone is a very soft stone made of a variety of talc. It is also a dense mineral that is often resistant to stains. 
• Fossilstone is also considered a limestone, which contains natural fossils such as sea shells and plants. 
• Travertine is usually a cream or reddish colour and formed through the accumulation of calcite in the hot springs. It contains lots of holes that were formed from water flowing through the stone. Normally, these holes are often filled with synthetic resins or cements. It required more maintenance if the holes are not filled. 

II) METAMORPHIC stone is originally come from a natural change from one type of stone to another through the combination of heat, pressure, and minerals. This change can be a process of crystallise formation, its texture change or its colours change. 

Figure 4: Marble Tiles

• Marble is a recrystallized limestone, which is formed when the limestone is softened by heat and pressure and recrystallized into marble where mineral changes occurred. The main elements are calcium and dolomite. It ranges in many colours and it is usually heavily veined which shows lots of grains. 

According to the Stone World, marble is classified into three categories: 

1. Dolomite : If it has more than 40% magnesium carbonate. 

2.Magnesian : If it has between 5% and 40% magnesium carbonate. 

3.Calcite : If it has less than 5% magnesium carbonate. 

• Slate is a fine grained metamorphic stone, which is formed from clay, sedimentary rock shale, and quartz. It is very thin and can be broken easily. Its colours are usually black, grey and green.

• Serpentine is identified by its marks which look like exactly the skin of a serpent. Mostly, its popular colours are green and brown. This stone contains serpentine minerals, which has lots of magnesium and an igneous origin. Besides, it does not always react well to recrystallization or so called diamond polished. 

III) IGNEOUS stones are mainly formed through volcanic material such as magma. As liquid magma cooled and solidified underneath the Earth surface, mineral gases and liquids penetrated into the stone and created new crystallise formations with various colours. 

Figure 5: Granite

• GRANITE is primarily made of Quartz (35%), Feldspar (45%) and Potassium. It usually has darker colours and provides a heavy crystalline and granular appearance with mineral grains. Granite is very hard material and much easier to maintain than marble. There are many different types of granite, which are depending on the percentage mix of quartz, mica and feldspar. For example, black granite is known as an Anorthosite, which contains very little quartz and feldspar and has a different composition than true granite. 

IV) MAN-MADE stones are made of unnatural mixtures such as cement with the additive of stone chips.

Figure 6: Terrazo

• Terrazzo is made of marble and granite chips embedded in a cement composition.
• Agglomerate or Conglomerate is made of marble chips embedded in a coloured resin composition.
• Cultured or Faux Marble is known as a mix of resins that are painted or mixed with a paint to look like marble.

Uses of stones as Building Materials


The uses of stones as building materials depend on its nature of works, type of structural element in which is used and its quality such as its appearances and its properties. For structural purpose, there are some stones are useful such as granite, limestone, slate and quartzite. 

• Foundation and Wall purpose: Quarry, split and sawn stones, which are obtained from massive rock by stone-cutting or stone-splitting machines, from rocks are mostly used to set up the substructure of buildings. Apart from that, piece stones sawn and split from limestone, sandstone, and dolomite are used for walls, piers, abutments.

• Facing and Architectural items: Facing slabs and stones, stairs, landings, and parapets are made of slabs sawn or split from semi-finished product blocks with glossy, dull, ground, sawn, pointed, fluted or rock finish such as granite, marble, limestone, sandstone and volcanic tuff are commonly used.

• Building items: Elements of stairs, landings, parapets and guard rails are manufactured from granite, marble, limestone, and volcanic tuff. Pedestal slabs and stones used for farming doorways and window-sill slabs are made from the same material as the facing slabs.

• Road Construction purpose: There are 3 types of stones, which are curb stones, paving blocks(ashlar) and cobble stone, used for paving purposes.

• Underground Structures and bridges:  They are built of slabs and stones from igneous (Granite) and sedimentary (Limestone) rocks. Tunnels and above-water elements of bridges are generally built of granite, diorite, gabbro, and basalt. Face stones and facing slabs for tunnels and bridges are given rock face, grooved or fluted finishes.

• Heat and Chemically Resistant Items: For high temperature conditions, they are mostly made from chromite, basalt, andesite and volcanic tuffs in order to resist high temperature. To resist against acids (except hydrofluoric acid and fluosilicic acids), slabs, which are usually made of granite and silicious stones, are generally used. On the other hand, limestone, dolomites, marble and magnesite show excellent resistance against alkalis.

This video shows natural stone production from deeLiving Manufacturing Stone Industry...so enjoy it...