This picture shows clearly how a quarry is built up. As you can see, the slabs of rock are located near the surface. This is what we call surface mining or open-faced quarry, a type of mining without underground activity. If the stone is located immediately below the surface, quarrying leaves huge holes in the landscape. After the quarrying is finished, the landscape is restored to its original state. Sometimes, the rock is found in a mountain rising high above the land.
A quarry is built up of several layers, sometimes referred to as benches. The natural separation between the benches is an important factor in determining how the natural stone will be used.
Some rocks are stratified, or layered. It is the layering that determines what stones will be extracted from the quarry. Stone blocks may be sliced with or against the vein. By changing the sawing direction, the stone acquires a completely different look. A vein cut stone may reveal well-defined parallel veins, whereas a cross-cut stone may result in a surface with light and dark clouded areas. As such, the same block of stone can be used in different applications.
Splitting stone benches
There are various techniques to split the primary slab horizontally and vertically from the quarry wall.
DRILLING – Long holes are drilled across the bench, at various distances, both horizontally and vertically. The slab is then extracted by inserting a small amount of explosives or expansive cement into the holes.
SAWING – A wire saw or chain saw is used to split the primary slab directly from the quarry wall. Expansive cushions or mechanical tools are used to complete separate the slab from the quarry wall.
Splitting the slabs without sawing
The long holes are filled with dynamite. Alternatively, hydraulic pressure or ice is used to separate the slabs. The amount of explosives is kept to a strict minimum, so as not to damage the ‘healthy’ stone.
Splitting the slabs with a band saw
Two kinds of saw can be used to extract slabs: a band saw and a chain saw. In case a band saw is used, the only holes made into the stone are the ones for putting the band through. The band is made up of diamond-coated segments. A drive wheel on rails makes for the sawing movement and ensures the required tension to extract a slab from the bench. Straight saw cuts are made directly into the quarry wall, both vertically and horizontally.
Splitting the slabs with a chain saw
This technique is used mainly if the length of the saw is ideal to get to the next bench or fault line. There is no need to drill holes and the saw may be used both vertically and horizontally. The saw may move on rails or be mounted to a tractor. This extraction method is mainly used for softer types of rocks, such as limestone or marble.
Once the primary slab has been separated from the bench, similar techniques are used to slice the slab into smaller blocks for commercial purposes : sawing, drilling and splitting. As a result, one slab may be split up into different blocks, that will each have a different application.
The size of the blocks depends on the structural features of the primary slab (veins, fault lines, etc.) and the intended use of the stone. Large blocks can be sawn into sheets, thin blocks may become tiles, small blocks may be directly processed into bespoke applications.
Transport inside the quarry
Large wheel loaders take the stone blocks from the quarry to the processing site. Blocks may be further processed at the quarry, for example sawn into stone sheets for bespoke solutions or into floor tiles. Blocks may also be processed at a stone sawmill.
If the quarry is quite deep, cables may be used to hoist the slabs. In case of heavy rain, using the normal routes may cause delays, and cables may be a good alternative.
Blocks for stone sheets
Blocks of a certain height are selected to be sawn into stone sheets, by either frame saws, block saws (disc saws) or wire saws. The fins of the frame saw are placed at a chosen distance from each other, so the slab may be fully used. Usually, the stone sheets are 2 or 3 cm thick.
Stone sheets may be up to 3.6m long and 2.0m high, depending on the material. In case block saws are used, the maximum height of the blocks depends on the diameter of the disc saw. As such, this technique is mostly used to obtain smaller and thicker sheets.
Sheets for tiles
Sheets come in all sizes. Large sheets are easy to deal with, as they can be sawn into exactly the required dimensions. Smaller sheets are frequently processed at sawmills, and can be used for sawing tiles, meaning the larger sheets can be reserved for bespoke applications. Some stones are more suitable to be cut into tiles. Tile manufacturers mostly use fully automatic tile machines and they will carefully select the blocks to ensure a minimum of material loss.
Sheets for custumization
Blocks of various sizes are used to produce decorative and massive pieces. Smaller blocks work best. Even today, manufacturers still make massive stone pillars. For that purpose, blocks of the right size are extracted from the quarry, to ensure minimal material loss. Another, more contemporary application are bluestone quay walls . Bluestone is frost-resistant, pressure-resistant (it has three times the pressure resistance of concrete) and generally quite sturdy, and is used even today to protect river banks.
From block to sheet
Block saws, frame saws and wire saws can be used to saw a block into sheets for bespoke applications. For instance, one single block can be sawn into different pieces that are all used for one and the same building project: sheets, tiles and even irregular shapes.
Surface treatment of a rough sheet
Once the block has been sawn into sheets of the right thickness, the pieces are further processed as per the customer’s requirements. There are different finishes : rough, honed or polished. Finishes that were traditionally reserved for bluestone, are now used on various materials, so that customers can choose from an almost endless range of possibilities.
Finishing and end product
The sheets are then sawn to the right size, either manually or mechanically, and finished, manually or not, to obtain the desired end product.
From sheet to end product
A bridge saw is used to saw the blocks into the required pieces. If a client needs both tiles and bespoke pieces, the tiles may be sawn out of the same block as the rest.
The finishing of natural stone always involves a synergy between man and machine. A machine makes the work of the stonecutter lighter, but it is the manual finishing that gives the end product its distinctiveness and brings out the timeless character.
Finishing and end products
Nowadays, machines can do lots of things, but craftsmen make the difference during the placement. Taking proper measurements is essential. Craftsmen from different disciplines share their expertise of natural stone, including the stone installer who is in charge of the final result.
Pool coping stones
Thanks to their versatility and frost-resistant properties, many types of natural stones are the perfect material for pool coping stones.
The versatility and elegance of natural stone makes it a popular choice for terraces, driveways and garden paths. As there is so much variety, intricate designs are possible. Concrete contains iron oxides, that change color after only a few years. Natural stone, on the contrary, lasts forever.
Thanks to its excellent wear-resistant properties, natural stone has always been used in places where many people come together. Natural stone is easy to use, beautiful to look at, and it makes your staircase into a real eye catcher.
The entrance hall of your house is frequently used and must be wear-resistant. An entrance hall in natural stone combined with a staircase in natural stone makes for a warm ambiance and adds value to your home.
Natural stone in all its variety is a great choice to give your kitchen an exclusive look. A countertop, a floor, a wall or even a sink in natural stone make your kitchen into a unique and contemporary space.
The bathroom, although less frequently used than other rooms, offers multiple possibilities to use natural stone. Bespoke elements, marble mosaics, floor tiles, wall cladding, everything goes. A massive stone bath tub remains quite expensive, but if you make the right choices, natural stone adds a touch of luxury without breaking the bank.