Antigorite - Mg3(Si2O5)(OH)4

Named in 1840 by Mathias Eduard Schweizer for the type locality, Valle di Antigorio, Domodossola, Piedmont, Italy, although there is a small question if he were on the Italian side of the border. Antigorite is a mineral belonging to the serpentine group of minerals. Antigorite forms during low-grade metamorphism of olivine-rich rocks (peridotite and other ultrabasic rocks, gabbros, lamprophyres, etc.); is a major component in serpentinites. Antigorite can be accompanied by lizardite which can form the major component in pseudomorphs after orthopyroxene.

Optical properties

• Color: Colourless; Fe-bearing varieties have a weak pleochroism from pale greenish-yellow to pale green.
• Form: Flaky, lath-shaped, parallel or felted fibrous masses, also dense.
• Interference colors: Low.
• Extinction: Tends to be straight.



Bibliography



• Bucher, K., & Grapes, R. (2011). Petrogenesis of metamorphic rocks. Springer Science & Business Media.
• Fossen, H. (2016). Structural geology. Cambridge University Press.
• Howie, R. A., Zussman, J., & Deer, W. (1992). An introduction to the rock-forming minerals (p. 696). Longman.
• Passchier, Cees W., Trouw, Rudolph A. J: Microtectonics (2005).
• Philpotts, A., & Ague, J. (2009). Principles of igneous and metamorphic petrology. Cambridge University Press.
• Shelley, D. (1993). Igneous and metamorphic rocks under the microscope: classification, textures, microstructures and mineral preferred-orientations.
• Vernon, R. H. & Clarke, G. L. (2008): Principles of Metamorphic Petrology. Cambridge University Press.
• Vernon, R. H. (2018). A practical guide to rock microstructure. Cambridge university press.


Photo
antigorite(4).jpg

Antigorite flaky crystals and relict olivine (high interference colors). Serpentinite from Sebino, Bergamo, Italy. XPL image, 10x (Field of view = 2mm)		 antigorite(5).jpg

Antigorite flaky crystals and relict olivine (high interference colors). Serpentinite from Sebino, Bergamo, Italy. XPL image, 10x (Field of view = 2mm)		 antigorite(6).jpg

Antigorite flaky crystals and relict olivine (high interference colors). Serpentinite from Sebino, Bergamo, Italy. XPL image, 10x (Field of view = 2mm)
antigorite(7).jpg

Antigorite flaky crystals and relict olivine (high interference colors). Serpentinite from Sebino, Bergamo, Italy. XPL image, 10x (Field of view = 2mm)		 antigorite(19).jpg

Antigorite flaky crystals and relict olivine (high interference colors). Serpentinite from Sebino, Bergamo, Italy. XPL image, 10x (Field of view = 2mm)		 antigorite(20).jpg

Antigorite flaky crystals and relict olivine (high interference colors). Serpentinite from Sebino, Bergamo, Italy. XPL image, 10x (Field of view = 2mm)
antigorite(21).jpg

Antigorite flaky crystals and relict olivine (high interference colors). Serpentinite from Sebino, Bergamo, Italy. XPL image, 10x (Field of view = 2mm)		 antigorite(17).jpg

Antigorite flaky crystals and relict olivine (high interference colors). Serpentinite from Sebino, Bergamo, Italy. XPL image, 10x (Field of view = 2mm)		 antigorite(16).jpg

Antigorite flaky crystals and relict pyroxenes (high interference colors). Serpentinite from Sebino, Bergamo, Italy. XPL image, 10x (Field of view = 2mm)
antigorite(18).jpg

Colorless Antigorite flaky crystals and relict olivine (high relief). Serpentinite from Sebino, Bergamo, Italy. PPL image, 10x (Field of view = 2mm)		 antigorite(22).jpg

Antigorite with gridlike texture and relict olivine (high interference colors). Serpentinite from Sebino, Bergamo, Italy. XPL image, 10x (Field of view = 2mm)		 antigorite(2).jpg

Antigorite flaky crystals in a deformed serpentinite. Sebino, Bergamo, Italy. XPL image, 2x (Field of view = 7mm)
antigorite(3).jpg

Antigorite flaky crystals in a deformed serpentinite. Sebino, Bergamo, Italy. XPL image, 2x (Field of view = 7mm)		 antigorite(10).jpg

Antigorite flaky crystals and relict pyroxenes (high interference colors). Serpentinite from Sebino, Bergamo, Italy. XPL image, 2x (Field of view = 7mm)		 antigorite(11).jpg

Antigorite flaky crystals and relict pyroxenes (high interference colors). Serpentinite from Sebino, Bergamo, Italy. XPL image, 2x (Field of view = 7mm)
antigorite(12).jpg

Antigorite flaky crystals and relict pyroxenes (high interference colors). Serpentinite from Sebino, Bergamo, Italy. XPL image, 2x (Field of view = 7mm)		 antigorite(13).jpg

Antigorite flaky crystals and relict pyroxenes (high interference colors). Serpentinite from Sebino, Bergamo, Italy. XPL image, 2x (Field of view = 7mm)		 antigorite(14).jpg

Antigorite flaky crystals and relict pyroxenes (high interference colors). Serpentinite from Sebino, Bergamo, Italy. XPL image, 2x (Field of view = 7mm)
antigorite(15).jpg

Antigorite flaky crystals and relict pyroxenes (high interference colors). Serpentinite from Sebino, Bergamo, Italy. XPL image, 2x (Field of view = 7mm)		 antigorite(23).jpg

Antigorite flaky crystals in a deformed serpentinite. Sebino, Bergamo, Italy. XPL image, 2x (Field of view = 7mm)		 antigorite(25).jpg

Antigorite flaky crystals in a deformed serpentinite. Sebino, Bergamo, Italy. XPL image, 2x (Field of view = 7mm)
antigorite2015g(1).jpg

Antigorite flaky crystals in a serpentinite. XPL image, 2x (Field of view = 7mm)		 antigorite2015g(2).jpg

Antigorite flaky crystals in a serpentinite. XPL image, 2x (Field of view = 7mm)		 antigorite2015g(3).jpg

Antigorite flaky crystals in a serpentinite. XPL image, 2x (Field of view = 7mm)
antigorite2015g(4).jpg

Antigorite flaky crystals in a serpentinite. XPL image, 2x (Field of view = 7mm)		 antigorite2015g(5).jpg

Antigorite flaky crystals in a serpentinite. XPL image, 2x (Field of view = 7mm)		 antigorite2015g(6).jpg

Antigorite flaky crystals in a serpentinite. XPL image, 2x (Field of view = 7mm)