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
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.