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Dickite

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Formula:
Al2(Si2O5)(OH)4
System:
Monoclinic
Colour:
White, or tinted by ...
Hardness:
2 - 2½
Name:
Named after Allan Brugh Dick (1833 - 1926), Scottish metallurgical chemist, who first described the species.
Kaolinite-Serpentine Group.

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

Classification of Dickite

Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
Explanation of status:
Dickite appears to be a polytype of kaolinite (as does nacrite).
9.ED.05

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

71 : PHYLLOSILICATES Sheets of Six-Membered Rings
1 : Sheets of 6-membered rings with 1:1 layers
15.6

15 : Silicates of Aluminum
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Type Occurrence of Dickite

Year of Discovery:
1930

Occurrences of Dickite

Geological Setting:
Usually of hydrothermal origin in conjunction 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:
2.60 g/cm3 (Measured)    2.62 g/cm3 (Calculated)

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 Data:
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°
Max Birefringence:
δ = 0.005 - 0.006
Image 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:
Al2(Si2O5)(OH)4
Essential elements:
All elements listed in formula:
Common Impurities:
Ti,Fe,Mg,Ca,Na,K

Relationship of Dickite to other Species

Other Members of Group:
AmesiteMg2Al(AlSiO5)(OH)4
AntigoriteMg3(Si2O5)(OH)4
Baumite(Mg,Al,Mn,Zn,Fe)3(Si,Al)2O5(OH)4
Berthierine(Fe2+,Fe3+,Al)3(Si,Al)2O5(OH)4
Brindleyite(Ni,Al)3(Si,Al)2O5(OH)4
Caryopilite(Mn,Mg)3(Si2O5)(OH)4
ChrysotileMg3(Si2O5)(OH)4
Clinochrysotile
CronstedtiteFe22+Fe3+((Si,Fe3+)2O5)(OH)4
Fraipontite(Zn,Al)3((Si,Al)2O5)(OH)4
GreenaliteFe2-3(Si2O5)(OH)4
HalloysiteAl2(Si2O5)(OH)4
KaoliniteAl2(Si2O5)(OH)4
KellyiteMn22+Al(AlSiO5)(OH)4
LizarditeMg3(Si2O5)(OH)4
ManandoniteLi2Al4(Si2AlB)O10(OH)8
NacriteAl2(Si2O5)(OH)4
Népouite(Ni,Mg)3(Si2O5)(OH)4
Odinite(Fe,Mg,Al,Fe,Ti,Mn)2.4((Si,Al)2O5)(OH)4
Orthochrysotile
Parachrysotile
PecoraiteNi3(Si2O5)(OH)4
Webskyite
Common Associates:
9.ED.05KaoliniteAl2(Si2O5)(OH)4
9.ED.05NacriteAl2(Si2O5)(OH)4
9.ED.05Odinite(Fe,Mg,Al,Fe,Ti,Mn)2.4((Si,Al)2O5)(OH)4
9.ED.10HalloysiteAl2(Si2O5)(OH)4
9.ED.10HisingeriteFe23+(Si2O5)(OH)4 · 2H2O
9.ED.10Halloysite-7ÅAl2(Si2O5)(OH)4
9.ED.15AmesiteMg2Al(AlSiO5)(OH)4
9.ED.15AntigoriteMg3(Si2O5)(OH)4
9.ED.15Berthierine(Fe2+,Fe3+,Al)3(Si,Al)2O5(OH)4
9.ED.15Brindleyite(Ni,Al)3(Si,Al)2O5(OH)4
9.ED.15Caryopilite(Mn,Mg)3(Si2O5)(OH)4
9.ED.15ChrysotileMg3(Si2O5)(OH)4
9.ED.15CronstedtiteFe22+Fe3+((Si,Fe3+)2O5)(OH)4
9.ED.15Fraipontite(Zn,Al)3((Si,Al)2O5)(OH)4
9.ED.15GreenaliteFe2-3(Si2O5)(OH)4
9.ED.15KellyiteMn22+Al(AlSiO5)(OH)4
9.ED.15LizarditeMg3(Si2O5)(OH)4
9.ED.15ManandoniteLi2Al4(Si2AlB)O10(OH)8
9.ED.15Népouite(Ni,Mg)3(Si2O5)(OH)4
9.ED.15PecoraiteNi3(Si2O5)(OH)4
9.ED.15GuidottiiteMn2Fe3+(Fe3+SiO5)(OH)4
9.ED.20Allophane(Al2O3)(SiO2)1.3-2 · 2.5-3H2O
9.ED.20ChrysocollaCu2-xAlx(H2-xSi2O5)(OH)4 · nH2O (x < 1)
9.ED.20ImogoliteAl2SiO3(OH)4
9.ED.20Neotocite(Mn,Fe,Mg)SiO3 · H2O
9.ED.25BismutoferriteFe23+Bi(SiO4)2(OH)
9.ED.25ChapmaniteFe23+Sb3+(Si2O5)O3(OH)
15.1AndalusiteAl2(SiO4)O
15.2KyaniteAl2(SiO4)O
15.3SillimaniteAl2(SiO4)O
15.4MulliteAl4+2xSi2-2xO10-x
15.5PyrophylliteAl2(Si4O10)(OH)2
15.7NacriteAl2(Si2O5)(OH)4
15.8KaoliniteAl2(Si2O5)(OH)4
15.9Metahalloysite
15.10HalloysiteAl2(Si2O5)(OH)4
15.11Allophane(Al2O3)(SiO2)1.3-2 · 2.5-3H2O
71.1.1.2KaoliniteAl2(Si2O5)(OH)4
71.1.1.3NacriteAl2(Si2O5)(OH)4
71.1.1.4HalloysiteAl2(Si2O5)(OH)4

Other Names for Dickite

Name in 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

Other Information

Health Risks:
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

Specimens:
The following Dickite specimens are currently listed for sale on minfind.com.

Localities for Dickite

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.
Mineral and/or Locality  
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