There are three basic types of rock: igneous, metamorphic and sedimentary. Igneous rock is broken down into two subtypes: intrusive igneous and extrusive igneous. Extrusive igneous stone comes in the form of stones like basalt, while intrusive igneous rock comes in the form of granite.

Granite is formed deep in the earth’s surface under great heat and pressure. Granite is formed from molten magma exceeding 4,000 degrees Fahrenheit and compressed for millions of years to produce some of the hardest material on Earth. Unlike metamorphic stone, granite’s base, or chemical makeup, is siliceous rather than calcerous.

Siliceous based stone is made from silica, similar to silica sand, and since it is composed of quartz, it is extremely hard, only slightly different than the makeup of a diamond. Diamonds are the hardest material known.

These facts are important when you consider purchasing natural stone for certain applications. Not all stone, even if it considered “hard” stone, is appropriate for all areas in your home or building.

Granite with its silicon base is impervious to almost any acidic items that you would use in your home. Most people don’t think of lemons or vinegar as something that would damage a surface of any kind, but they do when it comes to marble or almost any other metamorphic stone. Pure acids have been poured on granites and left there for some time. There is no effect, not even etching. Consumer Reports rated granite countertops as “the toughest surface that you can put in a kitchen, let alone the most dynamic”.

As more granite is discovered and the stone quarried in all parts of the world, the quantities available are staggering and the colors are nothing less than stunning. All the while, prices for this gorgeous commodity have dropped steadily for years. Twenty years ago the only buildings that afforded this natural beauty were government buildings and multi-million dollar homes. Much of the “old world” was built with these stones and is still here today, so it should certainly last in your kitchen. You may cut on your granite counters, but you will need to sharpen your fine cutlery more often. Granite boasts a general hardness on Mohs scale (a measure of hardness) of around 7 while a good high carbon knife will be about 5.

Lastly, the ability to clean this surface to pristine is incredible because of its density and burnished surface. Consumer Reports ranked it above all other surfaces to get clean except stainless steel.

Marble is often confused with granite but is only similar in that they are both stone. Marble is a metamorphic stone made over millions of years under great pressure. Most marbles are made of metamorphosed, or somewhat fossilized, sedimentary stone. Marble is calcerous and, therefore, less hard and susceptible to acids and scratching.

While marble is occasionally used for kitchen counters, it is not advisable. Marbles are suggested for fireplace mantels, hearths and surrounds. Columns, furniture tops, backsplashes, and vanities are other excellent applications for marble.

Marble Tile	Marble Slab	Marble Block