In addition to its use as a decorative building material, marble is also widely used in sculpture. Many of the most famous works of art by Michaelangelo and other Renaissance artists are made of marble, which is one of the reasons they are still around to be admired today.
What Is Marble?
Marble is a type of rock that usually is mined from the ground. Originally, it was limestone or dolomite. But over many millennia, the intense pressures of the Earth’s weight and heat from geothermic events pushed the molecules making up the limestone closer together. The result is an interlocking mosaic of carbonate crystals that form a harder, purer type of rock known as marble.
From a geological perspective, marble is considered to be metamorphosed limestone. Stonemasons, however, often use the term “marble” to describe any type of un-metamorphosed limestone.
Pure Marble vs Swirled Marble
Marble that is pure white is very rare. It is the result of metamorphism of a very pure limestone or dolomite protolith that has practically no silicates in it.
Conversely, marble that is colored, swirled, or has streaks or veins in it usually has mineral impurities including clay, sand, silt, iron oxide, or chert that were present in the original limestone prior to metamorphism.
Green marble is often due to serpentine that comes from limestone or dolostone with high magnesium and silica impurities.
Where Marble Comes From
Marble is valuable because it is rare. There are only a handful of places in the world where top-quality, nearly pure marble can be found.
Different geographic areas can produce marble with a distinctive color or pattern. For example, Carrara marble from Tuscany has a white or blue-gray color that makes it distinctly Italian.