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Perdões, Minas Gerais, Brazil
© Martins da Pedra
|System:||Monoclinic||Colour:||green, green-blue, ...|
|Hardness:||3½ - 4|
|Name:||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.|
The type material was collected near the border between Switzerland and Italy from outcrops of the Geisspfad serpentinite. It is not clear in which country the material was sampled.
m = 16 and m = 17 polysomes known.
See also the closely related chrysotile and lizardite.
Note: Antigorite is not the most common serpentine, although it is a common member of the group. Volumetrically, lizardite is the most abundant sepentine.
Visit gemdat.org for gemological information about Antigorite. Currently in public beta-test.
Classification of Antigorite
|Strunz 8th edition ID:||8/H.27-10|
|Nickel-Strunz 10th (pending) edition ID:||9.ED.15|
9 : SILICATES (Germanates)
E : Phyllosilicates
D : Phyllosilicates with kaolinite layers composed of tetrahedral and octahedral nets
|Dana 8th edition ID:||71.1.2a.1|
71 : PHYLLOSILICATES Sheets of Six-Membered Rings
1 : Sheets of 6-membered rings with 1:1 layers
|Hey's CIM Ref.:||14.4.15|
14 : Silicates not Containing Aluminum
4 : Silicates of Mg
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Type Occurrence of Antigorite
|Co-type Localities:||Antigorio Valley, Ossola Valley, Verbano-Cusio-Ossola Province, Piedmont, Italy|
Geisspfad area, Binn Valley, Wallis (Valais), Switzerland
|General Appearance of Type Material:||massive, scales, plates|
|Place of Conservation of Type Material:||ETH Zürich, Switzerland|
|Year of Discovery:||1840|
|Geological Setting of type material:||Serpentinite|
|Associated Minerals at type locality:|
Physical Properties of Antigorite
|Colour:||green, green-blue, white, brown, black|
|Hardness (Mohs):||3½ - 4|
|Density (measured):||2.5 - 2.6 g/cm3|
|Density (calculated):||2.52 g/cm3|
Crystallography of Antigorite
|Class (H-M):||m - Domatic|
|Cell Parameters:||a = 43.53Å, b = 9.25Å, c = 7.26Å|
β = 91.13°
|Ratio:||a:b:c = 4.706 : 1 : 0.785|
|Unit Cell Volume:||V 2,922.69 Å³ (Calculated from Unit Cell)|
|X-Ray Powder Diffraction:|
Optical Data of Antigorite
|RI values:||nα = 1.555 - 1.567 nβ = 1.560 - 1.573 nγ = 1.560 - 1.573|
|2V:||Measured: 20° to 50°|
|Maximum Birefringence:||δ = 0.005 - 0.006|
Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Chemical Properties of Antigorite
|Simplified for copy/paste:||Mg3(Si2O5)(OH)4|
|Essential elements:||H, Mg, O, Si|
|All elements listed in formula:||H, Mg, O, Si|
Relationship of Antigorite to other Species
|Member of:||Kaolinite-Serpentine Group|
|Other Members of Group:|
|Related Minerals - Nickel-Strunz Grouping):|
|Related Minerals - Hey's Index Grouping:|
Other Names for Antigorite
|Health Warning:||No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.|
References for Antigorite
Zussman, J. (1954): Investigation of the crystal structure of antigorite. Mineralogical Magazine: 30: 498-512.
Kunze, V.G. (1958): Die gewellte Struktur des Antigorits, II. Zeitschrift für Kristallographie: 110: 282-320.
Kunze, V.G. (1961): Antigorit. Fortschritte der Mineralogie: 39: 206-324.
Spinnler, G.E. (1985): HRTEM study of antigorite, pyroxene-serpentine reactions and chlorite, 248 p. PhD Thesis, Arizona State University, Tempe, Arizona.
Uehara, S. and Shirozu, H. (1985): Variations in chemical composition and structural properties of antigorites. Mineralogical Journal: 12: 299-318.
Mellini, M., Trommsdorff, V., and Compagnoni, R. (1987): Antigorite polysomatism: Behaviour during progressive metamorphism. Contributions to Mineralogy and Petrology: 97: 147-155.
Otten, M.T. (1993): High-resolution electron microscopy of polysomatism and stacking defects in antigorite. American Mineralogist: 78: 75-84.
Viti, C. and Mellini, M. (1996): Vein antigorite from Elba Island, Italy. European Journal of Mineralogy: 8: 423-434.
Wunder, B. and Schreyer, W. (1997): Antigorite: high-pressure stability in the system MgO-SiO2-H2O. Lithos: 41: 213-227.
Wunder, B., Baronnet, A., and Schreyer, W. (1997): Ab-initio synthesis and TEM confirmation of antigorite in the system MgO-SiO2-H2O. American Mineralogist: 82: 760-764.
Uehara, S. (1998): TEM and XRD study of antigorite superstructures. Canadian Mineralogist: 36: 1595-1605.
Wunder, B., Wirth, R., and Gottschalk, M. (2001): Antigorite: Pressure and temperature dependence of polysomatism and water content. European Journal of Mineralogy: 13: 485-495.
Dodony, I., Posfai, M., and Buseck, P.R. (2002): Revised structure models for antigorite: An HRTEM study. American Mineralogist: 87: 1443-1457.
Bromiley, G.D. and Pawley, A.R. (2003): The stability of antigorite in the systems MgO-SiO2-H2O (MSH) and MgO-Al2O3-SiO2-H2O (MASH): The effects of Al 3+ substitution on high-pressure stability. American Mineralogist: 88: 99-108.
Grobéty, B. (2003): Polytypes and higher-order structures of antigorite A TEM study. American Mineralogist: 88: 27-36.
Capitani, G.C. and Mellini, M. (2004): The modulated crystal structure of antigorite: the m = 17 polysome. American Mineralogist: 89: 147-158.
Capitani, G.C. and Mellini, M. (2005): HRTEM evidence for 8-reversals in the m = 17 antigorite polysome. American Mineralogist: 90: 991-999.
Capitani, G.C. and Mellini, M. (2006): The crystal structure of a second antigorite polysome (m = 16), by single-crystal synchrotron diffraction. American Mineralogist: 91: 394-399.
Internet Links for Antigorite
Localities for Antigorite
The map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.