Thaumasite Mineral Data

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.

Name Pronunciation:

Thaumasite + Pronunciation

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 - Dipyramidal H-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),

Physical Properties of Thaumasite

Cleavage:

{???} Poor

Color:

Colorless, White.

Density:

1.88 - 1.9, Average = 1.89

Diaphaneity:

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:

Fluorescent, Long UV=dull uneven white.

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
Ncalc = 1.49 - 1.5

Optical Data:

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

Calculated Properties of Thaumasite

Electron Density:

Bulk Density (Electron Density)=1.98 gm/cc
note: Specific Gravity of Thaumasite =1.89 gm/cc.

Fermion Index:

Fermion Index = 0.0032813823
Boson Index = 0.9967186177

Photoelectric:

PE_Thaumasite= 2.91 barns/electron
U=PE_Thaumasite x rElectron Density= 5.75 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Thaumasite is Not Radioactive

Thaumasite Classification

Dana Class:

32.04.04.04 (32)Compound Sulfates

(32.04)(hydrous) with poly-anionic formula

(32.04.04)Charlesite Group

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

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

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

32.04.04.04 Thaumasite Ca3Si(CO3)(SO4)(OH)6•12(H2O) P 6₃/m 6/m

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

Strunz Class:

07.DG.15 07 - SULFATES (SELENATES, TELLURATES)

07.D - Sulfates (selenates, etc.) with additional anions, with H2O

07.DG -With large and medium sized cations; with NO3, CO3, B(OH)4, SiO4 or IO3

07.DG.15 Bentorite Ca6(Cr,Al)2(SO4)3(OH)12•26(H2O) P 6₃/mmc 6/m 2/m 2/m

07.DG.15 Charlesite Ca6(Al,Si)2(SO4)2B(OH)4(OH,O)12•26(H2O) P 3₁c 3m

07.DG.15 Ettringite Ca6Al2(SO4)3(OH)12•26(H2O) P 6₃/mmc 6/m 2/m 2/m

07.DG.15 Jouravskite Ca3Mn(SO4,CO3)2(OH)6•12(H2O) P 6₃/m 6/m

07.DG.15 Sturmanite Ca6(Fe,Al,Mn)2(SO4)2[B(OH)4](OH)12•25(H2O) P 3₁c 3m

07.DG.15 Thaumasite Ca3Si(CO3)(SO4)(OH)6•12(H2O) P 6₃/m 6/m

07.DG.15 Buryatite! Ca3(Si,Fe,Al)[SO4][B(OH)4](OH,O)6•12(H2O) P 3₁c 3m

07.DG.15 Carraraite! Ca3Ge(OH)6(SO4)(CO3)•12H2O P 6₃/m, or P 6₃ Hex

Other Thaumasite Information

References:

NAME( Duda&Rejl90) PHYS. PROP.(Collectors Book of Fluorescent Minerals) OPTIC PROP.(Ford32)

See Also:

Links to other databases for Thaumasite :
1 - Alkali-Nuts(English)
2 - Alkali-Nuts(Francais)
3 - Am. Min. Crystal Structure Database
4 - Amethyst Galleries' Mineral Gallery
5 - Athena
6 - EUROmin Project
7 - Ecole des Mines de Paris
8 - GeoScienceWorld
9 - Google Images
10 - Google Scholar
11 - Handbook of Mineralogy (MinSocAm)
12 - Handbook of Mineralogy (UofA)
13 - MinDAT
14 - Mineralienatlas (Deutsch)
15 - Online Mineral Museum
16 - QUT Mineral Atlas
17 - Ruff.Info
18 - WWW-MINCRYST

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Thaumasite

Ca3Si(CO3)(SO4)(OH)6•12(H2O)
Dana No: 32.04.04.04 Strunz No: 07.DG.15
Locality:

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