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Dickite

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Formula:
Al
 
2
(Si
 
2
O
 
5
)(OH)
 
4
System:MonoclinicColour:White, or tinted by ...
Hardness:2 - 2½
Member of:Kaolinite-Serpentine Group
Name:Named after Allan Brugh Dick (1833 - 1926), Scottish metallurgical chemist, who first described the species.
Polymorph of:Halloysite, Kaolinite, Nacrite


Kaolinite-Serpentine Group.

A secondary mineral usually of hydrothermal origin in conjuncton with veins, derived in part from the alteration of aluminosilicate minerals; also occurs as an authigenic sedimentary phase.

Classification of Dickite

IMA status:Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
Explanation of status:Dickite appears to be a polytype of kaolinite (as does nacrite).
Strunz 8th edition ID:8/H.25-20
Nickel-Strunz 10th (pending) edition ID:9.ED.05

9 : SILICATES (Germanates)
E : Phyllosilicates
D : Phyllosilicates with kaolinite layers composed of tetrahedral and octahedral nets
Dana 7th edition ID:71.1.1.1
Dana 8th edition ID:71.1.1.1

71 : PHYLLOSILICATES Sheets of Six-Membered Rings
1 : Sheets of 6-membered rings with 1:1 layers
Hey's CIM Ref.:15.6

15 : Silicates of Aluminum
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Type Occurrence of Dickite

Type Locality:Pant-y-Gaseg Mine, Amlwch, Isle of Anglesey (Gwynedd; Anglesey), Wales, UK
Year of Discovery:1930

Occurrences of Dickite

Geological Setting:Usually of hydrothermal origin in conjuncton with veins, derived in part from the alteration of aluminosilicate minerals; also occurs as an authigenic sedimentary phase.

Physical Properties of Dickite

Diaphaneity (Transparency):Transparent
Comment:Lustre satiny.
Colour:White, or tinted by impurities
Hardness (Mohs):2 - 2½
Tenacity:Flexible
Cleavage:Perfect
On {001}, perfect.
Density (measured):2.60 g/cm3
Density (calculated):2.62 g/cm3

Crystallography of Dickite

Crystal System:Monoclinic
Class (H-M):m - Domatic
Space Group:Bb
Cell Parameters:a = 5.150Å, b = 8.940Å, c = 14.424Å
β = 96.8°
Ratio:a:b:c = 0.576 : 1 : 1.613
Unit Cell Volume:V 659.42 ų (Calculated from Unit Cell)
Z:4
Morphology:Crystals pseudohexagonal, elongated [100] at times. As aggregates of platelets resembling books. Masses of microscopic crystals.
X-Ray Powder Diffraction:
d-spacingIntensity
For dickite-2M1:(
(
7.15(100)
4.12(70)
3.80(60)
3.58(100)
2.51(50)
2.33(90)
1.975(50)
1.49(50)

Optical Data of Dickite

Type:Biaxial (+)
RI values: nα = 1.561 - 1.564 nβ = 1.561 - 1.566 nγ = 1.566 - 1.570
2V:Measured: 50° to 80°, Calculated: 72° to 80°
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:none

Chemical Properties of Dickite

Formula:
Al
 
2
(Si
 
2
O
 
5
)(OH)
 
4
Simplified for copy/paste:Al2(Si2O5)(OH)4
Essential elements:Al, H, O, Si
All elements listed in formula:Al, H, O, Si
Common Impurities:Ti,Fe,Mg,Ca,Na,K

Relationship of Dickite to other Species

Member of:Kaolinite-Serpentine Group
Other Members of Group:

- +
Amesite
Mg
 
2
Al(AlSiO
 
5
)(OH)
 
4
Antigorite
Mg
 
3
(Si
 
2
O
 
5
)(OH)
 
4
Baumite
(Mg,Al,Mn,Zn,Fe)
 
3
(Si,Al)
 
2
O
 
5
(OH)
 
4
Berthierine
(Fe
2+
 
,Fe
3+
 
,Al)
 
3
(Si,Al)
 
2
O
 
5
(OH)
 
4
Brindleyite
(Ni,Al)
 
3
(Si,Al)
 
2
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
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
Li
 
2
Al
 
4
(Si
 
2
AlB)O
 
10
(OH)
 
8
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
Webskyite
Common Associates:
Chalcedony
Related Minerals - Nickel-Strunz Grouping):

- +
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.15Antigorite
Mg
 
3
(Si
 
2
O
 
5
)(OH)
 
4
9.ED.15Berthierine
(Fe
2+
 
,Fe
3+
 
,Al)
 
3
(Si,Al)
 
2
O
 
5
(OH)
 
4
9.ED.15Brindleyite
(Ni,Al)
 
3
(Si,Al)
 
2
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
Li
 
2
Al
 
4
(Si
 
2
AlB)O
 
10
(OH)
 
8
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+
 
(Si
 
2
O
 
5
)O
 
3
(OH)
Related Minerals - Hey's Index Grouping:

- +
15.1Andalusite
Al
 
2
(SiO
 
4
)O
15.2Kyanite
Al
 
2
(SiO
 
4
)O
15.3Sillimanite
Al
 
2
(SiO
 
4
)O
15.4Mullite
Al
 
4+2x
Si
 
2-2x
O
 
10-x
15.5Pyrophyllite
Al
 
2
(Si
 
4
O
 
10
)(OH)
 
2
15.7Nacrite
Al
 
2
(Si
 
2
O
 
5
)(OH)
 
4
15.8Kaolinite
Al
 
2
(Si
 
2
O
 
5
)(OH)
 
4
15.9Metahalloysite
15.10Halloysite
Al
 
2
(Si
 
2
O
 
5
)(OH)
 
4
15.11Allophane
(Al
 
2
O
 
3
)(SiO
 
2
)
 
1.3-2
· 2.5-3H
 
2
O
Related Minerals - Dana Grouping):

- +
71.1.1.2Kaolinite
Al
 
2
(Si
 
2
O
 
5
)(OH)
 
4
71.1.1.3Nacrite
Al
 
2
(Si
 
2
O
 
5
)(OH)
 
4
71.1.1.4Halloysite
Al
 
2
(Si
 
2
O
 
5
)(OH)
 
4

Other Names for Dickite

Other Languages:
Dutch:Dickiet
German:Dickit
Italian:Dickite
Polish:Dickit
Russian:Диккит
Simplified Chinese:迪开石
地开石
迪凯石
Spanish:Dickita
Traditional Chinese:迪開石
地開石
迪凱石
Varieties:
Changhua StoneGaoshan Stone

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 Dickite

Reference List:

- +
Ross, C.S. and P.F. Kerr (1930) Dickite, a kaolin mineral. American Mineralogist: 15: 34-39.

Grim, R.E. (1953) Clay Mineralogy. McGraw Hill: 370.

Newnham, R.E. (1961) A refinement of the dickite structure and some remarks on polymorphism in kaolin minerals. Mineralogical Magazine: 32: 683-704.

Deer, W.A., R.A. Howie, and J. Zussman (1963) Rock-forming minerals, volume 3, sheet silicates: 194-212.

Sen Gupta, P.K., E.O. Schlemper, W.D. Johns, and F. Ross (1984) Hydrogen positions in dickite. Clays and Clay Minerals, 32, 483-485.

Joswig, W., Drits, V. A. (1986): The orientation of the hydroxyl groups in dickite by X-ray diffraction. Neues Jahrbuch für Mineralogie, Monatshefte 1986, 19-22.

Bish, D. L., Johnston, C. T. (1993): Rietveld refinement and Fourier-transform infrared spectroscopic study of the dickite structure at low temperature. Clays and Clay Minerals 41, 297-304.

Gaines, Richard V., H. Catherine, W. Skinner, Eugene E. Foord, Brian Mason, Abraham Rosenzweig (1997), Dana's New Mineralogy : The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana: 1407.

Farmer, V.C. (2000) Transverse and longitudinal crystal modes associated with OH stretching vibrations in single crystals of kaolinite and dickite. Spectrochimica Acta: A56: 927-930.

Balan E, Delattre S, Guillaumet M, Salje E K H (2010): Low-temperature infrared spectroscopic study of OH-stretching modes in kaolinite and dickite. American Mineralogist 95, 1257-1266.

Internet Links for Dickite

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  • Raman and XRD data at RRUFF project
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  • Localities for Dickite

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