Clastic marbles: fragments of rocks, cemented fossils as well as siliceous or calcareous materials are visible in the texture. Serpentine marbles: green colored marbles whose name derives from a particular group of minerals called the serpentine group which is mixed with limestone. Sometimes, it is possible to find them in darker shades close to blue or yellow based on which mineral of serpentine group is present in the majority within the marble. http://www.mqmarble.com/marble/blue-marble/