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From Mine to Home

History of Granite
The term granite is derived from the Latin word “granum” which means ‘grain’ due to its granular nature although for the Italian term of granite is from the past participle of granire which means to granulate or make grainy.

Granite is a very hard, crystalline, igneous rock primarily composed of feldspar, quartz, orthoclase or microcline accompanied by one or more dark minerals. It is visibly homogeneous in texture. It is the most common plutonic rock of the Earth's crust, forming by the cooling of magma (silicate melt) at depth.
Large granite bodies may have formed within earth’s crust by intrusion of new magma or by the re-melting of igneous varieties of crustal rocks. The evolutionary history of granite can be revealed by examining the chemistry of successive layers of its large constituent crystals, notably zircon. Granite is formed by the recycling of deep crustal rocks as mantle magma rose through them, rather than by re-melting the ancient, shallower crust, as was widely believed.

Granite is typically medium to coarse grained, occasionally with some individual crystals larger than the groundmass forming a rock known as porphyry. Granite can be pink to dark gray or even black, depending on their chemistry and mineralogy. Outcrops of granite tend to form tors, rounded massifs, and terrains of rounded boulders cropping out of flat, sandy soils. Granite sometimes can occur in circular depressions surrounded by a range of hills, formed by the metamorphic aureole or hornfels.
Granite is nearly always massive, hard and tough, and it is for this reason it has gained widespread use as a construction stone. The average density of granite is 2.75 g•cm-3 with a range of 1.74 g•cm-3 to 2.80 g•cm-3. The word granite comes from the Latin granum, a grain, in reference to the coarse-grained structure of such a crystalline rock. For this reason granite is used as a building material in the form of granite tiles and granite slabs for wall cladding, roofing, flooring, a variety of other interior and exterior applications and especially for counter tops, kitchen work tops and vanity units and is the most popular material for monuments and memorials. Granite has a prominent place among dimensional stones on account of its hardness, resistance to weathering, capability to take mirror polish, fascinating colours and textural patterns.

Despite being fairly common throughout the world, the areas with the most commercial granite quarries are located in the Scandinavian Peninsula (mostly in Finland and Norway), Spain (mostly Galicia and Extremadura), Brazil, India and several countries in the South end of the African continent, namely Angola, Namibia, Zimbabwe and South Africa.

Mining Process

Granite is an igneous, magma-formed rock that is generally made up of quartz, feldspar and mica. These minerals combine in varying percentages that account for the color, veining and crystallization patterns that make each granite deposit — and therefore customized countertop — unique. Other minerals, such as magnetite, pyrite, garnet and hematite can occur in much smaller amounts, and as such, it is these different combinations that create the wide range of granite varieties that are available throughout the world.

Mining & Processing

Granite is quarried across the globe since there are very few quarries which have mining machinery, mining for granite is a manual job which uses hand chisels and hammers for drilling.

Years ago, excavating granite was a timely, laborious process that included the use of a significant amount of explosives and a lot of manual labor in the drilling process. Today, diamond wire saws and slot drilling are the primary activities used to complete the job, making granite more economical for consumers, as well as a cleaner, safer and significantly less labor-intensive excavation process.

Granite quarry is a pit or some open excavation from which granite is obtained. To obtain granite from a quarry digging, cutting or blasting process is used. This process of obtaining the stone is called quarrying. Once quarrying is done, the processing of granite starts.

Granite quarries are laid out based on the direction in which the granite will break the easiest, providing the maximum benefit that can be attained from the natural seams and structure. By using these natural seams, the maximum yield can be obtained from the quarry deposit, thus reducing the amount of stone produced that is not suitable for use as dimensional granite.

The types of natural fractures that can be seen in a granite deposit are based on their relationship to the flow lines, as well as the surface of the granite deposit. Sheeting joints run roughly parallel to the topographic surface at various levels beneath the surface; longitudinal joints are steep cracks that run parallel to the flow lines; while cross joints are perpendicular to the flow lines.

Granites are now mined in most of the Indian states for use as construction material and road metal but production of dressed granite blocks and slabs from Andhra Pradesh, Karnataka, Rajasthan and Tamil Nadu are highly priced. In India there are 43 granite processing units of which 12 are in Andhra Pradesh, 13 in Karnataka, 3 in Rajasthan, 14 in Tamil Nadu and 1 in Orissa.

The recovery of marketable grade granite is reported to be 32 to 40 per cent in Karnataka, 25 to 75 per cent in four quarries around Jalore, the main granite mining centre of Rajasthan, and 20 to 40 per cent in Tamil Nadu.

Over the years, granite has developed from a largely structural material affordable only to the wealthy, to a stone that has numerous applications — countertops quickly becoming one of the most popular — and greater availability and mass appeal. One of the reasons for this increase in accessibility is the advance of technology used to quarry the stone.

With new technology it minimized the costs thus bringing granite into homes all across the world. Whereas in the past, excavating granite from a deposit required an elaborate process of drilling, pounding, sawing and blasting, now — with the use of diamond wire saws, which look like wires, but are covered in diamond segments — quarry workers are able to saw whole blocks of granite in a faster and more streamlined manner.

Granite is available in a wide variety of colors, including white, black, pink and red. The varying percentages of quartz, feldspar and mica account for the rock's color, veining and crystallization, making each granite deposit unique. The high presence of quartz can account for many of granite's color variations, as quartz can be milky white, rose, smoky, yellow or amethyst. Feldspar, another one of granite's main minerals, can account for a glassy white, blue, green or red appearance. Finally, mica can contribute to a black, green, red, yellow or brown appearance.

Facts

Quarry Locations:
  • Europe: Austria, Belgium, the Czech Republic, Finland, France, Germany, Italy, Norway, Portugal, Sardinia, Spain, Sweden, Switzerland, Venezuela

  • Africa: Angola, Egypt, Madagascar, Namibia, Nigeria, South Africa

  • Asia: China, Egypt, India, Iran, Saudi Arabia, Sri Lanka, Taiwan, Thailand, Turkey, Ukraine, Vietnam

  • Australia
Applications:
  • Architectural accessories
  • Interior accessories
  • Building stone
  • Countertops
  • Fireplaces
  • Flooring
  • Landscaping
  • Appropriate Finishes
  • Bush hammered
  • Flamed
  • Honed
  • Polished
  • Sandblasted
  • Sawn (rough)
Stone Stats:
  • Average MOHs Hardness: 7
  • Average Absorption Rate (%): .13
  • Average Bulk Density (pcf): 172.8
  • Average Compressive Strength (psi): 23,300
  • Average Modulus of Rupture (psi): 1,855
Photo Gallery:

Quarry Block Yard
quarry Block Yard
quarry Chinese man working in a granite quarry
Working in a quarry in India Mining in India –Old times

How Granite Slabs are Created

Granite is more than just a pretty face. The stone is second only to diamonds in hardness, which accounts for the effectiveness of diamonds in facilitating the quarrying of the natural stone. It is granite's toughness and durability that make it such a desirable countertop material. It won't break or crack, and it is virtually scratch and stain resistant.

Cutting granite at the quarry

Once the granite is removed from the earth, it needs to be cut to size accordingly. This is typically done with wire saws that are often treated with a varying range of abrasives from sand to aluminum oxide to diamond, along with water which acts as a coolant. Other types of cutting devices are often used in tandem, or in the absence of, these wire saws. Water jet cutting, for example, uses a focused, high-pressure stream to cut stone along specified cutting lines. Once it has been established that the granite blocks are to be used for countertops and tile, they are cut and polished into the familiar forms for these purposes. The granite tile and slabs are calibrated to ensure that the thickness of the granite is uniform and gauged to make sure that they are square; tiles are beveled to produce their smooth edges. Once this part of the process is completed, they are ready for your project.

There are four operations that are involved in the processing of granite. They are:
Dressing
Cutting/Sawing
Surface Grinding and Polishing
Edge-Cutting-Trimming.

Dressing Granite

Stone dressing: once a block of granite has been broken down to the appropriate size required, the sides have to be roughly smoothed off before polishing can begin. Stone dressing was usually carried out at stone-cutting and polishing works, rather than at the quarry itself.

Originally, rough dressing was done with a blocking hammer or a dressing pick, with puncheons and chisels for finer work. A more efficient dressing tool was the bush hammer, or patent axe.


Cutting/Sawing

Cutting of granite blocks into slabs was once a laborious process taking months, using an iron saw with sand and water as an abrasive. With the invention of chilled iron shot (small pellets of iron) and the use of steel saws, the cutting time was reduced to days. The dressing process left a relatively smooth surface which could then be polished.

During the 1960s, endless wire loop saws superseded the old frame saws thus diamond tipped circular saws have also been used for many years since it leaves a surface sufficiently smooth as to require no further polishing before dressing.

The rough blocks arriving at the stone yard from the quarry are irregular in size and shape is inspected to identify the most efficient way to cut them into slab form while minimizing wastage.

Once the initial inspection is complete, the block is primarily sawed into slab form by means of large circular diamond-tipped blades, wire or monoblade saws which cut one slab at a time or by a frame saw with multiple blades that cut each block – depending upon its size – in a single operation into a number of slabs.

With this operation the thickness of the block can be varied to suit the finished stone it is being cut for, and it is only when the block is opened in this way that any internal defects can be discovered. It is important to remember that stone is a natural product and that colour and veining (figuring) may also vary throughout a block or from block to block and result in some slabs being rejected.

The next phase – secondary sawing – consists of cutting the slabs into dimensioned ashlar. The machines used are usually computerised bridge saws with circular diamond blades ranging in diameter from 600-1200mm and can also have tilting heads to provide angled cuts.

The resulting ashlar is coded ready for palleting or sent to the mason workshop for other masonry work such as broaching, droving or stugging to take place. In the second of these options slabs can also be cut to sizes and shapes that can be moulded by hand or, equally common today, by means of lathes profiling and water jetting machines (these machines are mostly controlled by computers).

The stone that passes through the lathes, profiling and water jetting machines can either be returned to the secondary saws to be jointed or moved to the banker area for the masons to carry out further work such as returning moulding, sunk mouldings or to cut out moulded brackets in a cornice course. Following the completion of work to each stone it is checked for quality and any defects before being polished, palleted and ‘shrink-wrapped’ ready for delivery to site.

The banker area is where time-served masons and apprentices using traditional tools such as mells (mallets), teeth tools, chisels, etc. carry out work that cannot be undertaken by machines.

Nowadays most of their chisels have tungsten instead of steel tips and – instead of employing the blacksmith of former years – are sharpened by use of grinding wheels. The masons may now also use compressed air tools and angle grinders along with drilling and coring machines.

Surface Grinding/Polishing

Dressing of stone left a roughly flat but uneven surface; polishing produces a smooth, even shiny surface. For thousands of years the only way to polish stone was to rub one against another, using sand and water as an abrasive. Polishing machines were introduced in the early nineteenth century. Flat iron rings were turned by hand over a dressed surface, using sand and water as an abrasive. Steam power for turning the iron rings was introduced in 1830s.

In the 1880s the Jenny Lind polishing machine was introduced (the machine so called from its humming noise, which was likened to the Swedish singer of that name).

This had a steel ring - shooting ring - which rotated over the dressed stone surface, iron shot and water were used as an abrasive. Finer polishing stages used carborundum then emery.

With modern saws leaving smoother finishes, the shooting process is unnecessary, and carborundum polishing can begin immediately. A modern version of the Jenny Lind, the Seaton polisher, has four small rotating solid carborundum heads and is often fully automatic.

A building’s architectural expression can be greatly enhanced by the choice of surface finish and in the case of natural stone a variety of considerations apply, including the function, type, and hardness of the material as well as the aesthetic effect desired. Greater awareness of the range of light and shade effects possible on different stone types and of the techniques available to draw out the unique qualities of each has increased demand for manually dressed stone, and this traditional process has become easier and quicker with new types of compressed air tools and machines.

Depending upon a stone’s intended application, material strength and the minimum thickness needed to withstand differing processing pressures, it is now possible to apply all kinds of finishing techniques. Final surface character is determined by the fineness of the applied finish used and can bring out a stone’s mineral content, colour, texture and structure.

Not all the listed finishes can be applied to every stone type, e.g. only sufficiently hard and dense stones such as granite can have a polished finish (the finest), but honed and fine-rubbed finishes are achievable

Edge/Cutting & Trimming

Carving of granite was always a long difficult process, not speeded up until the introduction of compressed air drills with tungsten tipped chisels. Polishing of detailed intricate carvings was carried out by rubbing the surface with stone using sand as an abrasive. When chilled iron shot came into use, shotting fiddles were used, with emery and tin oxide putting for later polishing stages.


Slab Photos

Gold & Silver Golden Ayrton
Matrix Louise Blue
Labareda Gold/Lapidus Gold Snow Flake
Juparana Casablanca Juparana Superclassico
Soapstone Juparana Bordeaux
Golden Musk/Verde Fantastico Lady Dream
Labrador Antique Artic Rainbow
Arandis Blue Pearl GB
Bianco Romano Bross Blue

Grading Granite Slabs

Granite is a natural stone which is quite unique since, unlike man-made materials, these natural stones will show a variation in colour and texture. With this in mind, the grading process is based on the variation of colour and characteristics of the granite.

Quality Differences
• First Choice Quality—here the granite is what the name says, the finest quality ever. With the first choice quality granite upon receipt one only needs to do is cut the granite slab to size, profile, etc during the fabrication process. The polishing process should no show any visual defects and be of a high gloss surface. With first choice quality granite during the fabrication process the amount of waste material is quite low.
• Commercial Quality—typically with this grade the granite will not polish quite as well and obvious visual defects such as blotches or small natural hairline cracks are present. However, a good fabricator and sawyer will have the ability to use the granite slab to its fullest potential.
• Second Quality—this grade of granite typically is used for larger contract or larger projects where the granite slabs are to be cut into smaller modules. The granite will have several repairable natural defects along with blotches. However, for the experienced fabricator this is a smart way to reduce costs on raw material although it will take more time to make the best granite slab.
• Caveat Emptor - Buyer beware!

International Standards

• Depth—the depth of polish should be a minimum of 95%.
• Length / Width—the granite slabs are given a 2 cm allowance from the narrowest point of measurement.
• Measurement—keep in mind that granite is a natural stone thus you may not be able to obtain a guarantee in length and widths. You should always be offered the estimated slab measurements prior to sawing the blocks in order for you to decide if the slab is suitable for your project.

• Pre-cut Slabs—granite slabs which are a stock item should have already been measured and are ready to ship. Pre-cut slabs can be inspected independently and verified if so required.
• Resin Filler—granite slabs which contain a natural open-veined formation will have a suitable resin filler applied to them.
• Slab Thickness—granite slabs sawn with a gang saw will have a tolerance of +/- ½ mm to the thickness of the granite slab. Along with this the polished face will be level.

• Tile Thickness—granite slabs fabricated for tiles will be produced to +/- ½ mm of the desired thickness.
• Colour Enhancer—unless specifically requested granite slabs do not use colour enhancers.

Transporting Granite

Typically a large number of companies use flatbed trucks to transport granite slabs since the granite rock slabs vary in weight from hundreds to thousands of pounds. The granite slabs are transported vertically on storage racks which are typically constructed of metal and/or wood in an A-frame structure. The granite slabs are then strapped in onto this A-frame structure and loaded onto the flat bed by the distributor. The slabs may be secured transversely and vertically to the frames prior to loading. Shoring prevents the frames from moving vertically and tipping. Direct lashing is used to prevent any lengthwise movement of the slabs.

Transporting granite slabs can be a difficult process since the loads can shift or if the granite is being transported by train the tracks can actually become deformed or fail.

Transportation Process

>>Preparing granite slabs for shipment
>> Once the granite has been cut, trimmed and polished it is prepared for delivery. The manufacture can utilize trucks, sea or trains as a method of getting the granite to the customer.
>> The granite slabs are packed in strong weatherproof wooden crates which have been fumigated. Typically the crates can bundles of 8 – 10 ¾” granite slabs having the capacity to hold 400 - 450 square feet. Each bundle weighs 2.6 tons, or 5,700 pounds. Every slab is protected by a thin plastic sheet placed between slabs along with a piece of wood which is placed beneath the slabs.
>> The granite slabs are now ready to be transported to the nearest shipping port for subsequent delivery to the UK.


Manufacturing Granite Worktops

Granite stones from the quarry look like a huge boulder yet the granite slab undergoes several processes turning the granite slab into a beautiful piece of stonework for you kitchen worktop.

Transporting the granite slab

Typically one views the transport of the granite stone as just loading it onto a truck and it is on its way to the manufacturer. However, unprocessed granite stones have a tendency to rub against each other thus grinding each other to pieces while in transport. If the granite slabs are not transported correctly the manufacturers could end up with a pile of stone dust.

The hauling trucks are fitted with containers which keep the granite stones packed in tight preventing movement. Once they reach their destination the granite slabs are gently unloaded with huge cranes.

Cutting

Precision cutting is the key element which is required to cut the granite stones which stone-cutting saws are used. For worktops, the granite slabs are cut into slabs 1 – 2” thick which gives stonecutters and fabricators more room to work with. The stone-cutting saws are typically diamond-tipped to prevent a sharp, hard cutting edge. Once the slabs have been cut, pressurized water is used on the edges of the granite stone. This process will refine the granite stone along with removing the coarseness around the granite slab’s rim. These water jets used for cutting stone maintain a water pressure of over 100 lbs per square; the water itself travels over 200 miles per hour.

Profiling/Finishing

The granite slabs are ready for finishing once they have been cut to the correct shape. This process involves sanding the piece with several buffers and different grades of sandpaper. Imagine doing this by hand, sounds tedious thus many manufacturers have machines to do this for them. The profiling process will create the shine for which the granite worktops are valued.

Typically an unfinished granite worktop will chip and break due to imperfections on the surface so profiling is used to help harden and clean the surface of the granite worktop.

Customization

The exact customization is based on what the granite piece is actually going to be used for, once the customer has given their specifications the piece is finely detailed prior to its being ready to be used. A typical kitchen worktop should have a hole for the sink cut out into the center of the granite worktop. Again, after the cut the rough edges will again be sanded away. Clips and support pins for the sink itself are also added onto the kitchen worktops.

Some granite worktops do not require a hole to be cut however; some customers prefer more texture in their granite worktop. At this point the master craftsmen use a hammer and chisel to create curlicues and geometric designs along the edge or in the center of the piece.

Finally, the piece is wrapped in bubble plastic, secured with duct tape, and is ready to be transported and installed. The entire process, from unrefined stone to finished usable countertop, usually takes less than a day, with pieces that require heavy detailing taking more time.

Installation

Granite worktops are crated and shipped upright and must be unloaded and unpacked upright. You will also never want to carry the granite worktop flat, always in the upright position otherwise you will risk fracturing it. However, nothing spruces up a kitchen better, faster, and easier that a new granite worktop. Bring a sketch with very accurate dimensions or eliminate any risk by taking advantage of the dealer's professional measuring services. Once the top has been cut to size, you can begin installation.

Tools Required

>> Straight edge
>> Spirit level
>> Tri-square
>> Drill bits with suitable drill for granite
>> Suitable saw (Hand held) for granite
>> Jig Saw (for wood)
>> Polishing heads
>> Adhesive (Araldite / Polyurethane)

Prepare the base—using a tri-square make sure the cabinet corners are square and level by using a spirit level. The existing cabinets should be firmly fixed in place before the installation of a granite worktop.

Sink cut-out—prior to actually installing your new granite worktop you need to make the sink cut which can be done for a drop-in or under mount sink. To do these mark the granite surface using the manufacturer’s template leaving sufficient margin from the front to the rear edge. Carefully place the granite slab on a workbench and cut the granite slab along the marking. You may want to do this step outside due to the excess dust it will create. Finally polish up the inside edge of the granite slab along with the sink top and the granite slab is now ready for installation.

Laying the granite slab—Measure against your base cabinets in order to obtain the correct measurements to cut your new granite slab to the correct measurement. Now place the granite slab on the base aligning it square to the front end of the cabinet. Use a level and adjust as necessary, if needed. Remove the granite slab, apply glue to the cabinet frame and place the granite slab on the cabinet base and allow it to set. If you need to make any adjustments do it prior to the glue hardening. Use steel brackets to secure the granite worktop to the frame from underneath. Continue this process for all other granite slabs you have to install.

Butt the seam joints—the edges which are to be seamed must be thoroughly cleaned along with making sure that the edges are straight and square to the granite worktop. Align the edge and surface of the two sections, using araldite for the seam joint and tightly butt the granite worktops. Use mineral spirits to clean the surface of the joint to remove any excess adhesive. You may want to use clamps to bind the two granite worktops together during the hardening process removing them immediately when the araldite has hardened.

Sealing the worktop—now that the installation is complete the surface should be sealed in order to protect the granite worktop from staining. To do these apply the sealer on top of the surface allowing it to ‘sit’ for 10 minutes. After 10 minutes clean up the excess sealer with a clean cloth according to the manufacturer’s recommendations. Allow the adhesives a minimum of 48 hours to dry then apply a second coat to protect the granite surface against bacteria and mildew.



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