Marble is a metamorphic rock that forms when limestone is subjected to the heat and pressure of metamorphism. It is composed primarily of the mineral calcite and usually contains other minerals, such as micas, quartz, pyrite, iron oxides. When acidic elements come in contact with calcium carbonate, it creates an etch. An etch is not a scratch. 

Rather, it is merely the removal of polished finish on the surface. Marble can come in a polished or honed finish. It is softer than granite, so the best application for it is on fireplace surrounds, bathroom, some furniture, and in generally less-traveled areas. Marble is rated as a three on the Mohs Hardness Scale.