Thaumasite Mineral Data

Thaumasite Mineral Data +

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General Thaumasite Information

Chemical Formula:

Ca3Si(CO3)(SO4)(OH)6·12(H2O)

Composition:

Molecular Weight = 622.62 gm

Calcium 19.31 % Ca 27.02 % CaO

Silicon 4.51 % Si 9.65 % SiO₂

Hydrogen 4.86 % H 43.40 % H₂O

Carbon 1.93 % C 7.07 % CO₂

Sulfur 5.15 % S 12.86 % SO₃

Oxygen 64.24 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Ca₃Si(CO₃)(SO₄)(OH)₆·12(H₂O)

IMA Status:

Valid Species (Pre-IMA) 1878

Locality:

Bjelke mine, near Areskutan, Jamtland, Sweden. Link to MinDat.org Location Data.

Name Origin:

From the Greek thaumasion - "surprising" in allusion to the chemical composition.

Synonym:

ICSD 31247

PDF 25-128

Thaumasite Image

Images:

Thaumasite

Comments: Doubly-terminated Thaumasite.
Location: N'Chwaning Mine, Kalahari Manganese Field, Northern Cape Province, South Africa. Scale: 1 cm across.
© John Veevaert

Images:

Thaumasite

Comments: Transparent crystal of thaumasite.
Location: N'Chwaning Mine, Kalahari Manganese Field, Northern Cape Province, South Africa. Scale: 1.1 x 0.4 cm.
© John Veevaert

Thaumasite Crystallography

Axial Ratios:

a:c = 1:0.94288

Cell Dimensions:

a = 11.03, c = 10.4, Z = 2; V = 1,095.76 Den(Calc)= 1.89

Crystal System:

Hexagonal - DipyramidalH-M Symbol (6/m) Space Group: P 6₃/m

$Help on X Ray Diffraction:$ X Ray Diffraction:

By Intensity(I/I_o): 9.56(1), 5.51(0.4), 3.41(0.2),

Crystal Structure:

Mouse
drag1 - LMB Manipulate Structure
drag2 - RMB Resize/Rotate
Keyboard
S - Stereo Pair on/off
H - Help Screen
I - Data Info
A - Atoms On/Off
P - Polyhedra On/Off
B - Bonds On/Off
Help on Above

Jacobsen S D , Smyth J R , Swope R J , Physics and Chemistry of Minerals , 30 (2003) p.321-329, Thermal expansion of hydrated six-coordinated silicon in thaumasite,, Ca3Si(OH)6(CO3)(SO4).12H2O, Sample: T = 130 K, Locality: unknown

View Additional jPOWD Structure files for Thaumasite
[1]

Physical Properties of Thaumasite

Cleavage:

[???] Poor

Color:

Colorless, White.

Density:

1.88 - 1.9, Average = 1.89

Diaphaniety:

Transparent to translucent

Fracture:

Brittle - Conchoidal - Very brittle fracture producing small, conchoidal fragments.

Habit:

Fibrous - Crystals made up of fibers.

Habit:

Massive - Fibrous - Distinctly fibrous fine-grained forms.

Habit:

Radial - Crystals radiate from a center without producing stellar forms (e.g. stibnite)

Hardness:

3.5 - Copper Penny

Luminescence:

None.

Luster:

Vitreous - Silky

Magnetism:

Nonmagnetic

Streak:

white

Optical Properties of Thaumasite

Dichroism (e):

none.

Dichroism (w):

none.

Gladstone-Dale:

CI meas= 0.016 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= 0.016 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2579,KPDmeas= 0.2579,KC= 0.2621

Optical Data:

Uniaxial (-), e=1.468, w=1.507, bire=0.0390.

Calculated Properties of Thaumasite

Electron Density:

r_electron=1.98 gm/cc
note: r_Thaumasite=1.89 gm/cc.

Fermion Index

Fermion Index = 0.00328
Boson Index = 0.99672

Photoelectric:

PE_Thaumasite= 2.91 barns/electron
U=PE_Thaumasite x r_electron= 5.75 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Thaumasite is Not Radioactive

Thaumasite Classification

Dana Class:

32.4.4.4 (32)Compound Sulfates

(32.4)(hydrous) with poly-anionic formula

(32.4.4)Dana Group

32.4.4.1 Charlesite Ca6(Al,Si)2(SO4)2B(OH)4(OH,O)12·26(H2O) P 3₁c 3m

32.4.4.2 Sturmanite Ca6(Fe,Al,Mn)2(SO4)2[B(OH)4](OH)12·25(H2O) P 3₁c 3m

32.4.4.3 Jouravskite Ca3Mn(SO4,CO3)2(OH)6·12(H2O) P 6₃/m 6/m

32.4.4.4 Thaumasite Ca3Si(CO3)(SO4)(OH)6·12(H2O) P 6₃/m 6/m

32.4.4.5 Carraraite! Ca3Ge(OH)6(SO4)(CO3)·12H2O P 6₃/m, or P 6₃ Hex

Strunz Class:

VIII/B.22-90 VIII - Silicates

VIII/B - Nesosubsilicates, with anions unfamiliar to tetraheders, cationes with coordinationnumber between [8] and [12]

VIII/B.22 - Thaumasite series

VIII/B.22-10 Hatrurite Ca3SiO5 R 3m 3m

VIII/B.22-25 Poldervaartite (Ca,Mn)2SiO3(OH)2 P bca 2/m 2/m 2/m

VIII/B.22-30 Afwillite Ca3Si2O4(OH)6 P 2₁ 2

VIII/B.22-40 Bultfonteinite Ca2SiO2(OH,F)4 P1 1

VIII/B.22-50 Spurrite Ca5(SiO4)2(CO3) P 2₁/a 2/m

VIII/B.22-60 Paraspurrite Ca5(SiO4)2(CO3) P 2₁/a 2/m

VIII/B.22-65 Ternesite! Ca5(SiO4)2SO4 P nma 2/m 2/m 2/m

VIII/B.22-70 Nagelschmidtite Ca7(SiO4)3(PO4)2 Unk Hex

VIII/B.22-75 Harrisonite! Ca(Fe,Mg)6(PO4)2(SiO4)2 R 3m 3 2/m

VIII/B.22-80 Fukalite Ca4Si2O6(CO3)(OH,F)2 Unk Ortho

VIII/B.22-90 Thaumasite Ca3Si(CO3)(SO4)(OH)6·12(H2O) P 6₃/m 6/m

VIII/B.22-100 Chelyabinskite* (Ca,Mg)3Si(OH)6(SO4,CO3)2·9(H2O) Unk Ortho

Other Thaumasite Information

References:

NAME( Duda&Rejl90) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Ford32)

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Thaumasite

Ca3Si(CO3)(SO4)(OH)6·12(H2O)
Dana No: 32.4.4.4 Strunz No: VIII/B.22-90
Locality:

Notes: