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Dickite

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Formula:
Al2(Si2O5)(OH)4
Colour:
White, or tinted by impurities
Hardness:
2 - 2½
Specific Gravity:
2.60
Crystal System:
Monoclinic
Name:
Named after Allan Brugh Dick (31 May 1833, Edinburgh, Scotland - 12 June 1926, Hampstead, London, UK), 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

Approved, 'Grandfathered' (first described prior to 1959)
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

Physical Properties of Dickite

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

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
IMA Formula:
Al2Si2O5(OH)4
Common Impurities:
Ti,Fe,Mg,Ca,Na,K

Crystallography of Dickite

Crystal System:
Monoclinic
Class (H-M):
m - Domatic
Space Group:
Bb
Cell Parameters:
a = 5.150 Å, b = 8.940 Å, c = 14.424 Å
β = 96.8°
Ratio:
a:b:c = 0.576 : 1 : 1.613
Unit Cell 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

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)

Type Occurrence of Dickite

Other Language Names for Dickite

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 of Dickite

Changhua Stone

A dense yellow variety of dickite, which is used for carving. It usually contains small amounts of alunite as an impurity.

Gaoshan Stone

A dense variety of dickite with red spots of hematite, which is used for carving. It also contains quartz and pyrophyllite as minor impurities. The Chinese consider this material as a variety of Shoushan stone, although true Shoushan stone mainly consists...

Relationship of Dickite to other Species

Other Members of this group:
Greenalite(Fe2+,Fe3+)2-3Si2O5(OH)4
HalloysiteAl2(Si2O5)(OH)4
KaoliniteAl2(Si2O5)(OH)4
ManandoniteLi2Al4(Si2AlB)O10(OH)8
NacriteAl2(Si2O5)(OH)4
Odinite(Fe,Mg,Al,Fe,Ti,Mn)2.4((Si,Al)2O5)(OH)4
Serpentine SubgroupD3[Si2O5](OH)4 D= Mg, Fe, Ni, Mn, Al, Zn

Common Associates

Associated Minerals Based on Photo Data:
Quartz29 photos of Dickite associated with Quartz on mindat.org.
Dolomite20 photos of Dickite associated with Dolomite on mindat.org.
Siderite11 photos of Dickite associated with Siderite on mindat.org.
Azurite9 photos of Dickite associated with Azurite on mindat.org.
Sphalerite8 photos of Dickite associated with Sphalerite on mindat.org.
Fluorite7 photos of Dickite associated with Fluorite on mindat.org.
Galena6 photos of Dickite associated with Galena on mindat.org.
Pyrite6 photos of Dickite associated with Pyrite on mindat.org.
Aragonite6 photos of Dickite associated with Aragonite on mindat.org.
Chalcopyrite6 photos of Dickite associated with Chalcopyrite on mindat.org.

Related Minerals - Nickel-Strunz Grouping

9.ED.Clinochrysotile
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.10HisingeriteFe3+2(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.15CaryopiliteMn2+3Si2O5(OH)4
9.ED.15ChrysotileMg3(Si2O5)(OH)4
9.ED.15CronstedtiteFe2+2Fe3+((Si,Fe3+)2O5)(OH)4
9.ED.15Fraipontite(Zn,Al)3((Si,Al)2O5)(OH)4
9.ED.15Greenalite(Fe2+,Fe3+)2-3Si2O5(OH)4
9.ED.15KellyiteMn2+2Al(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
9.ED.20ImogoliteAl2SiO3(OH)4
9.ED.20Neotocite(Mn,Fe,Mg)SiO3 · H2O
9.ED.25BismutoferriteFe3+2Bi(SiO4)2(OH)
9.ED.25ChapmaniteFe3+2Sb3+(Si2O5)O3(OH)

Related Minerals - Hey's Chemical Index of Minerals Grouping

15.1AndalusiteAl2(SiO4)O
15.2KyaniteAl2(SiO4)O
15.3SillimaniteAl2(SiO4)O
15.4MulliteAl4+2xSi2-2xO10-x
15.5PyrophylliteAl2Si4O10(OH)2
15.7NacriteAl2(Si2O5)(OH)4
15.8KaoliniteAl2(Si2O5)(OH)4
15.9MetahalloysiteAl2(Si2O5)(OH)4
15.10HalloysiteAl2(Si2O5)(OH)4
15.11Allophane(Al2O3)(SiO2)1.3-2 · 2.5-3H2O

Related Minerals - Dana Grouping (8th Ed.)

71.1.1.4HalloysiteAl2(Si2O5)(OH)4
71.1.1.5Odinite(Fe,Mg,Al,Fe,Ti,Mn)2.4((Si,Al)2O5)(OH)4

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:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Ross, C.S., Kerr, P.F. (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., Howie, R.A., Zussman, J. (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, R.V., Skinner, H.C.W., Foord, E.E., Mason, B., Rosenzweig, A. (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

mindat.org URL:
https://www.mindat.org/min-1287.html
Please feel free to link to this page.
Specimens:
The following Dickite specimens are currently listed for sale on minfind.com.

Localities for Dickite

Mineral and/or Locality  
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