English: Marble & dolomitized marble in the Precambrian of New York State, USA.

Marble is a crystalline-textured metamorphic rock composed of calcite (CaCO3 - calcium carbonate). It bubbles in acid and does not scratch glass. Marble forms by the metamorphism of limestone, a common biogenic sedimentary rock.

The outcrop seen here is composed of whitish marble (mosty banded) that is graphitic and phlogopitic. Some incorporated calc-silicate rock clasts having reaction rims are present.

The brownish band of rock with black staining in this photo is dolomitized marble. That is not the same as dolomitic marble, which is metamorphosed dolostone and dominated by the mineral dolomite (CaMg(CO3)2 - calcium magnesium carbonate). Dolomitized marble is calcitic marble that has been subsequently altered - in this case, by hot, Mg-bearing hydrothermal fluids that moved along a fracture. The alteration zone resembles a dike, but it's not.

The rocks here are part of the Gouverneur Marble of New York State's Adirondack Lowlands. The original limestones were metamorphosed at about 1.1 billion years ago, during the Grenville Orogeny.

Stratigraphy: Gouverneur Marble, Oswegatchie Group, Mesoproterozoic, ~1.1 Ga metamorphic age

Locality: Antwerp North Outcrop - roadcut on the southeastern side of Route 11, north of the town of Antwerp, Adirondack Lowlands, northern New York State, USA (44° 14’ 05.50” North latitude, 75° 36’ 01.83” West longitude)