The true marbles are calcitic, crystalline-textured metamorphic rocks. They form by intermediate- to high-grade metamorphism of limestones. They have been used for millennia as building and monument stones (e.g., ancient Greek & Roman archaeological sites and Michelangelo's sculptures).
White Carrara Marble - a finely-crystalline white marble with grayish wisps and mottling. This rock comes from the Apuan Marble Formation, the result of Tertiary metamorphism of lowermost Jurassic limestones. The unit is exposed in the Apuan Alps of northern Italy. White Carrara Marble was used to make Michelangelo's world-famous statue of David. This sample comes from the Carbonera Quarry in Massa-Carrara Province, far-northwestern Tuscany, northern Italy.
Danby White Marble - a whitish marble with grayish mottling that comes from the vicinity of Danby, Vermont, USA. The rock is quarried from the Shelburne Formation, an Ordovician limestone unit that was metamorphosed in the Pennsylvanian during the Allegheny Orogeny.