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Antigorite

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Perdões, Minas Gerais, Brazil
© Martins da Pedra

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Formula:
Mg
 
3
(Si
 
2
O
 
5
)(OH)
 
4
System:MonoclinicColour:green, green-blue, ...
Hardness:3½ - 4
Member of:Serpentine Group
Name:Named after the type locality, Valle di Antigorio, Domodossola, Piedmont, Italy


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.

Kaolinite-Serpentine group.

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

IMA status:Approved
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:
Olivine

Physical Properties of Antigorite

Lustre:Vitreous
Diaphaneity (Transparency):Transparent
Colour:green, green-blue, white, brown, black
Streak:greenish white
Hardness (Mohs):3½ - 4
Cleavage:Distinct/Good
[001] good
Fracture:Splintery
Density (measured):2.5 - 2.6 g/cm3
Density (calculated):2.52 g/cm3

Crystallography of Antigorite

Crystal System:Monoclinic
Class (H-M):m - Domatic
Space Group:Bm {B1 1m} {Cm} {C1m1}
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 ų (Calculated from Unit Cell)
X-Ray Powder Diffraction:
d-spacingIntensity
7.28 (100)
7.21 (10)
3.623 (60)
3.589 (10)
2.523 (30)
2.169 (10)
2.150 (10)
1.558 (10)

Optical Data of Antigorite

Type:Biaxial (-)
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.
Surface Relief:Low
Dispersion:weak

Chemical Properties of Antigorite

Formula:
Mg
 
3
(Si
 
2
O
 
5
)(OH)
 
4
Essential elements:H, Mg, O, Si
All elements listed in formula:H, Mg, O, Si
Common Impurities:Ni,Al,Mn

Relationship of Antigorite to other Species

Member of:Serpentine Group
Other Members of Group:

- +
Amesite
Mg
 
2
Al(AlSiO
 
5
)(OH)
 
4
Baumite
(Mg,Al,Mn,Zn,Fe)
 
3
(Si,Al)
 
2
O
 
5
(OH)
 
4
Berthierine
(Fe
2+
 
,Fe
3+
 
,AlMg)
 
2-3
((Si,Al)
 
2
O
 
5
)(OH)
 
4
Brindleyite
(Ni,Mg,Fe)
 
2
(Al(Si,Al)O
 
5
)(OH)
 
4
Caryopilite
(Mn,Mg)
 
3
(Si
 
2
O
 
5
)(OH)
 
4
Chrysotile
Mg
 
3
(Si
 
2
O
 
5
)(OH)
 
4
Clinochrysotile
Cronstedtite
Fe
2+
2
Fe
3+
 
((Si,Fe
3+
 
)
 
2
O
 
5
)(OH)
 
4
Dickite
Al
 
2
(Si
 
2
O
 
5
)(OH)
 
4
Fraipontite
(Zn,Al)
 
3
((Si,Al)
 
2
O
 
5
)(OH)
 
4
Greenalite
Fe
 
2-3
(Si
 
2
O
 
5
)(OH)
 
4
Halloysite
Al
 
2
(Si
 
2
O
 
5
)(OH)
 
4
Kaolinite
Al
 
2
(Si
 
2
O
 
5
)(OH)
 
4
Kellyite
Mn
2+
2
Al(AlSiO
 
5
)(OH)
 
4
Lizardite
Mg
 
3
(Si
 
2
O
 
5
)(OH)
 
4
Manandonite
LiAl
 
4
(BSi
 
3
O
 
10
)(OH)
 
6
Nacrite
Al
 
2
(Si
 
2
O
 
5
)(OH)
 
4
Népouite
(Ni,Mg)
 
3
(Si
 
2
O
 
5
)(OH)
 
4
Odinite
(Fe,Mg,Al,Fe,Ti,Mn)
 
2.4
((Si,Al)
 
2
O
 
5
)(OH)
 
4
Orthochrysotile
Parachrysotile
Pecoraite
Ni
 
3
(Si
 
2
O
 
5
)(OH)
 
4
Vorhauserite
Related Minerals - Nickel-Strunz Grouping):

- +
9.ED.05Dickite
Al
 
2
(Si
 
2
O
 
5
)(OH)
 
4
9.ED.05Kaolinite
Al
 
2
(Si
 
2
O
 
5
)(OH)
 
4
9.ED.05Nacrite
Al
 
2
(Si
 
2
O
 
5
)(OH)
 
4
9.ED.05Odinite
(Fe,Mg,Al,Fe,Ti,Mn)
 
2.4
((Si,Al)
 
2
O
 
5
)(OH)
 
4
9.ED.10Halloysite
Al
 
2
(Si
 
2
O
 
5
)(OH)
 
4
9.ED.10Hisingerite
Fe
3+
2
(Si
 
2
O
 
5
)(OH)
 
4
 · 2H
 
2
O
9.ED.10Halloysite-7Å
Al
 
2
(Si
 
2
O
 
5
)(OH)
 
4
9.ED.15Amesite
Mg
 
2
Al(AlSiO
 
5
)(OH)
 
4
9.ED.15Berthierine
(Fe
2+
 
,Fe
3+
 
,AlMg)
 
2-3
((Si,Al)
 
2
O
 
5
)(OH)
 
4
9.ED.15Brindleyite
(Ni,Mg,Fe)
 
2
(Al(Si,Al)O
 
5
)(OH)
 
4
9.ED.15Caryopilite
(Mn,Mg)
 
3
(Si
 
2
O
 
5
)(OH)
 
4
9.ED.15Chrysotile
Mg
 
3
(Si
 
2
O
 
5
)(OH)
 
4
9.ED.15Cronstedtite
Fe
2+
2
Fe
3+
 
((Si,Fe
3+
 
)
 
2
O
 
5
)(OH)
 
4
9.ED.15Fraipontite
(Zn,Al)
 
3
((Si,Al)
 
2
O
 
5
)(OH)
 
4
9.ED.15Greenalite
Fe
 
2-3
(Si
 
2
O
 
5
)(OH)
 
4
9.ED.15Kellyite
Mn
2+
2
Al(AlSiO
 
5
)(OH)
 
4
9.ED.15Lizardite
Mg
 
3
(Si
 
2
O
 
5
)(OH)
 
4
9.ED.15Manandonite
LiAl
 
4
(BSi
 
3
O
 
10
)(OH)
 
6
9.ED.15Népouite
(Ni,Mg)
 
3
(Si
 
2
O
 
5
)(OH)
 
4
9.ED.15Pecoraite
Ni
 
3
(Si
 
2
O
 
5
)(OH)
 
4
9.ED.15Guidottiite
Mn
 
2
Fe
3+
 
(Fe
3+
 
SiO
 
5
)(OH)
 
4
9.ED.20Allophane
(Al
 
2
O
 
3
)(SiO
 
2
)
 
1.3-2
 · 2.5-3H
 
2
O
9.ED.20Chrysocolla
Cu
 
2-x
Al
 
x
(H
 
2-x
Si
 
2
O
 
5
)(OH)
 
4
 · nH
 
2
O (x < 1)
9.ED.20Imogolite
Al
 
2
SiO
 
3
(OH)
 
4
9.ED.20Neotocite
(Mn,Fe,Mg)SiO
 
3
 · H
 
2
O
9.ED.25Bismutoferrite
Fe
3+
2
Bi(SiO
 
4
)
 
2
(OH)
9.ED.25Chapmanite
Fe
3+
2
Sb
3+
 
(SiO
 
4
)
 
2
(OH)
Related Minerals - Hey's Index Grouping:

- +
14.4.1Forsterite
Mg
 
2
SiO
 
4
14.4.2Enstatite
MgSiO
 
3
14.4.3Clinoenstatite
MgSiO
 
3
14.4.4Chrysotile
Mg
 
3
(Si
 
2
O
 
5
)(OH)
 
4
14.4.5Clinochrysotile
14.4.6Orthochrysotile
14.4.7Parachrysotile
14.4.8Lizardite
Mg
 
3
(Si
 
2
O
 
5
)(OH)
 
4
14.4.9Talc
Mg
 
3
(Si
 
4
O
 
10
)(OH)
 
2
14.4.10Spadaite
MgSiO
 
2
(OH)
 
2
 · H
 
2
O (?)
14.4.11Sepiolite
Mg
 
4
(Si
 
6
O
 
15
)(OH)
 
2
 · 6H
 
2
O
14.4.12Loughlinite
Na
 
2
Mg
 
3
Si
 
6
O
 
16
 · 8H
 
2
O
14.4.13Eifelite
KNa
 
3
Mg
 
4
Si
 
12
O
 
30
14.4.14Stevensite
(Ca,Na)
 
x
Mg
 
3-x
(Si
 
4
O
 
10
)(OH)
 
2
14.4.16 Magnesio-anthophyllite

Other Names for Antigorite

Synonyms:
BaltimoriteBastard AsbestosGymniteIron-GymniteNickel-Gymnite
PorcellophiteProtoantigoriteSepteantigoriteThermophylliteYu yen shi stone
Yu yen stoneZermattite
Other Languages:
German:Antigorit
Baltimorit
Blätterserpentin
Eisengymnit
Gymnit
Nickelgymnit
Porcellophit
Septeantigorit
Zermattit
Russian:Антигорит
Simplified Chinese:叶蛇纹石
Spanish:Antigorita
Baltimorita
Gymnita
Porcellophita
Septeantigorita
Zermattita
Varieties:
Al-AntigoriteAndes JadeBoweniteJenkinsitePicrolite
VorhauseriteWilliamsite

Other Information

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

Reference List:

- +
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

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