4105 GREAT NORTH ROAD, GLEN EDEN, AUCKLAND PHONE (09) 818 5261

Granite

Why use Granite?
 
Granite - The Earth's Oldest Building Material
 
Granite is quite literally as old as the earth.  It is formed from liquid magma, the molten rock still found at the core of the planet, cooled slowly to form a substance approaching the hardness and durability of diamond. Granite is a igneous rock the name reflecting its fiery beginnings.  However, granite owes its hardness and density to the fact that it has been solidified deep within the earth, under extreme pressure.  Over the eons, seismic activity has changed the crust of the planet, forcing veins of granite to the surface.

Glaciers scraped off layers of dirt, sand and rock to expose granite formations. Typically revealed by outcrops, these deposits have been discovered on all of the continents. This durability makes granite the ideal material for memorials ensuring the required longevity.

Granite is sourced from many continents around the world and although they differ in quality and crystalline structure all granites have three essential minerals in common:
 
Feldspar (50% or greater)
Quartz (25 – 30%)
Mica (3 – 10%)

These minerals occur in varying proportions giving granite its own natural colour, texture and structural characteristics.

In addition, hornblende, magnite, hematite, pyrite, zircon, garnet, corundum and other minerals may be present in smaller amounts, adding to the unique colouration and texture of each granite deposit.

  With a natural material like granite a certain amount of "movement" or grain in the stone must be expected.  Many people find this blending of colours to be the most compelling reason for using granite.  From the moh's hardness scale of 1-10 granite falls within the 6-7 ranges whereas a diamond is 10.

World Sources of Granite

The majority of the world continent have deposits of indigenous granite.  However, in many cases due to young age of the continent or because of the substructure sound granite blocks cannot be sourced economically.  The world's major granite producing countries are South Africa, North and South America, Sweden, Finland, Norway and India.

Australia also has huge tracts of granite which are used extensively throughout Australia whilst in New Zealand our commercially used granite is restricted to Coromandel granite.  Bluff granite was used quite extensively during the 1940's and 1950's - this quarry is no longer viable.


Quarrying Granite

Granite has been quarried systematically as far back as 4000 BC long before hardened metals were used.  Over the centuries quarrying techniques changed very little, remaining relatively unsophisticated.  Then in the late 1880's new quarrying technologies  were introduced that made it possible to use granite as a cost effective building or monumental stone.  Quarrying operations were then modernised by using compressed air to drive rock drills, outlining the block with closely spaced holes.  Then wedges could be used to break loose blocks of specified sizes and shapes. 

Quarrying techology continues to advance.  One method of quarrying granite uses a gas flame to burn channels along the sides of a block.  Then holes are drilled with gang drills along the back and bottom of the block.  Soft explosives are used to separate the "quarried-to-order" granite piece.  A front end loader can then lift the block from the quarry and load it on a truck bed for shipment to the fabrication plant.

Block Saw-724
A block of raw black granite being cut into slabs by a large diamond tipped saw.
IMG 006 New-page-001-77
Typical stone quarry face

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Stone block being transported

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Excessive weight for fork loader

 
     
4105 Great North Road
Glen Eden
Auckland 0602
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SAT 9:00am - 12pm