Ophicalcite

Serpentinites containing carbonate minerals in appreciable amounts are referred to as ophicarbonates (ophicalcite, ophimagnesite, ophi..). Ophicarbonates typically form from carbonate-free serpentinites by reaction with crustal CO₂ given off by progressive decarbonation reactions in carbonate-bearing metasediments. Serpentinites are very efficient CO₂ buffers and small amounts of CO₂ in a fluid are sufficient to convert serpentine assemblages into carbonate-bearing assemblages.

Ophicarbonate
A rock consisting of serpentinite and carbonate; the serpentinite is commonly fragmented or brecciated, and veined and impregnated by the carbonate material (calcite, dolomite, or magnesite). It forms by the serpentinisation of ultramafic rocks and their reaction with CO₂ solutions. Hence ophimagnesite (where the carbonate is predominantly magnesite), etc.

Ophicalcite
Strictly a form of ophicarbonate in which calcite is the predominant carbonate. However, the term has traditionally been used in the meaning of ophicarbonate, that is, it is taken to include rocks containing a variety of different carbonates.

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Carbonate veins in a Ophicarbonate.

Carbonate veins in a Ophicarbonate.

Bibliography

• David Shelley (1983): Igneous and metamorphic rocks under the microscope. Campman & Hall editori.
• E. WM. Heinrich (1956): Microscopic Petrografy. Mcgraw-hill book company,inc
• Anthony R. Phillpotts & Jay J. Ague: Principles of igneous and metamorphic petrology. Cambridge editore.
• Passchier, Cees W., Trouw, Rudolph A. J: Microtectonics (2005)

Photo
Areas rich in serpentine (gray) and areas rich in calcite. Ophicalcite from Lanzada-scermendone (valmalenco), central Alps (Italy). XPL image, 2x (Field of view = 7mm)	Areas rich in serpentine (gray) and areas rich in calcite. Ophicalcite from Lanzada-scermendone (valmalenco), central Alps (Italy). XPL image, 2x (Field of view = 7mm)	Areas rich in serpentine (gray) and areas rich in calcite. Ophicalcite from Lanzada-scermendone (valmalenco), central Alps (Italy). XPL image, 2x (Field of view = 7mm)
Areas rich in serpentine (gray) and areas rich in calcite. Ophicalcite from Lanzada-scermendone (valmalenco), central Alps (Italy). XPL image, 2x (Field of view = 7mm)	Areas rich in serpentine (gray) and areas rich in calcite. Ophicalcite from Lanzada-scermendone (valmalenco), central Alps (Italy). XPL image, 2x (Field of view = 7mm)	Areas rich in serpentine (gray) and areas rich in calcite. Ophicalcite from Lanzada-scermendone (valmalenco), central Alps (Italy). XPL image, 2x (Field of view = 7mm)
Areas rich in serpentine (gray) and areas rich in calcite. Ophicalcite from Lanzada-scermendone (valmalenco), central Alps (Italy). XPL image, 2x (Field of view = 7mm)	Areas rich in serpentine (gray) and areas rich in calcite. Ophicalcite from Lanzada-scermendone (valmalenco), central Alps (Italy). XPL image, 2x (Field of view = 7mm)	Areas rich in serpentine (colorless) and areas rich in calcite. Ophicalcite from Lanzada-scermendone (valmalenco), central Alps (Italy). PPL image, 2x (Field of view = 7mm)
Areas rich in serpentine (gray) and areas rich in calcite. Ophicalcite from Lanzada-scermendone (valmalenco), central Alps (Italy). XPL image, 2x (Field of view = 7mm)	Areas rich in serpentine (colorless) and areas rich in calcite. Ophicalcite from Lanzada-scermendone (valmalenco), central Alps (Italy). PPL image, 2x (Field of view = 7mm)	Areas rich in serpentine (gray) and areas rich in calcite. Ophicalcite from Lanzada-scermendone (valmalenco), central Alps (Italy). XPL image, 2x (Field of view = 7mm)
Areas rich in serpentine (gray) and areas rich in calcite. Ophicalcite from Lanzada-scermendone (valmalenco), central Alps (Italy). XPL image, 2x (Field of view = 7mm)	Areas rich in serpentine (gray) and areas rich in calcite. Ophicalcite from Lanzada-scermendone (valmalenco), central Alps (Italy). XPL image, 2x (Field of view = 7mm)	Areas rich in serpentine (gray) and areas rich in calcite. Ophicalcite from Lanzada-scermendone (valmalenco), central Alps (Italy). XPL image, 2x (Field of view = 7mm)
Calcite veins in a Ophicalcite. Valle lagorara, alta Val di vara, Spezia, Italy. PPL image, 2x (Field of view = 7mm)	Calcite veins in a Ophicalcite. Valle lagorara, alta Val di vara, Spezia, Italy. XPL image, 2x (Field of view = 7mm)	Calcite veins in a Ophicalcite. Valle lagorara, alta Val di vara, Spezia, Italy. PPL image, 2x (Field of view = 7mm)
Calcite veins in a Ophicalcite. Valle lagorara, alta Val di vara, Spezia, Italy. XPL image, 2x (Field of view = 7mm)	Calcite veins in a Ophicalcite. Valle lagorara, alta Val di vara, Spezia, Italy. XPL image, 2x (Field of view = 7mm)	Calcite veins in a Ophicalcite. Valle lagorara, alta Val di vara, Spezia, Italy. XPL image, 2x (Field of view = 7mm)
Calcite veins in a Ophicalcite. Valle lagorara, alta Val di vara, Spezia, Italy. PPL image, 2x (Field of view = 7mm)	Calcite veins in a Ophicalcite. Valle lagorara, alta Val di vara, Spezia, Italy. XPL image, 2x (Field of view = 7mm)	Calcite veins in a Ophicalcite. Valle lagorara, alta Val di vara, Spezia, Italy. XPL image, 2x (Field of view = 7mm)