Marble 
is a recrystallized limestone formed by the effects of heat and pressure. Composed mainly of calcium and dolomite. Ranging in hardness from 3 to 4 on the MOH scale, it is best used on vertical surfaces, vanity tops, and lightly used flooring. Due to the characteristics of this stone it is not recommended for use in kitchen applications. 

Many people think of marble as a white stone with gray veigning, in reality marble is available in a variety of colors.