What is the difference between granite and marble?
Granite (from the Latin granito, meaning ‘grained’) is volcanic or igneous rock. Formed from deep within the earth’s crust millions of years ago, granite has been cooled from molten rock and subjected to enormous pressures and heat as it rose to the surface. Different quantities of mica, feldspar, and quartz give the variety of colours and patterns found in the different granites around the world. It is also this process that makes it scratch resistant and heatproof in daily use and as hard as ,er, granite !
Marble, by contrast is a metamorphic rock. Formed by compression of millions of tiny fossilized shells into calcium carbonate, in its purest form it is a white like the Italian Carrara marble. In other areas the water percolating down through the rock introduces different minerals whose reaction causes the spectacular colouring and veining so prized for centuries. It is still possible to find small fossils within the stone. Marble is spectacularly beautiful but because of its porosity of it is prone to staining by such things as red wine and oil. This is why granite is the preferred type of stone for kitchen worktops, while marble is generally used for bathrooms. If you really have to have marble in the kitchen (and these remarks would also apply to limestone, slate and honed granite) then great care must be taken to keep it well sealed.
Where does the granite come from?
Granite is mined all over the world and our Colour Charts page indicates the countries of origin. Our staff will always be glad to advise the origin of any other granite or marble you are interested in.
How does it get here?
Granite is quarried out of the ground in big blocks of (say) 2.5 metres by 1.5 metres by 1.5 metres. Each block is then sawn into slices, usually 20mm or 30mm thick, by a huge sawing machine which has a bank of diamond-tipped saw blades attached to a reciprocating arm, somewhat similar to a bread slicer. For granite, the whole sawing process takes about 5 to 7 days for each block! Once sawn, the finish on the granite is dull, so each slab is laid flat and one face is polished seven times with successively finer grades of diamond tools to achieve a fantastic polished finish. County Granite and Marble will inspect and purchase either the whole block or many slabs from each block to ensure consistency of colouring and graining for each job. We in turn will then cut shape and polish the edges with seven grades of diamond tools to achieve the same standard of finish.
Why is granite good for kitchen worktops?
Although granite is also slightly porous it is dimensionally stable (doesn’t warp!)in wet areas and does not have absorbent end grain in the same way that wood and laminated chipboard do. This means that it is an ideal material for undermounted and Belfast sinks, and can incorporate drainer grooves or sunken sloping draining areas within the granite itself.