Tobermorite Mineral Data

Tobermorite Mineral Data +

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General Tobermorite Information

Chemical Formula:

Ca5Si6O16(OH)2·4(H2O)

Composition:

Molecular Weight = 702.36 gm

Calcium 24.54 % Ca 34.33 % CaO

Aluminum 1.92 % Al 3.63 % Al₂O₃

Silicon 21.99 % Si 47.05 % SiO₂

Hydrogen 1.44 % H 12.82 % H₂O

Oxygen 50.11 % O

______ ______

100.00 % 97.84 % = TOTAL OXIDE

Empirical Formula:

Ca_4.3Si_5.5Al_0.5O₁₆(OH)₂·4(H₂O)

Environment:

A hydrothermal alteration product of calcium carbonate rocks, due to contact metamorphism and metasomatism. Filling vesicles and cavities in basaltic rocks.

IMA Status:

Valid Species (Pre-IMA) 1880

Locality:

In Scotland, on the Isle of Mull, around Tobermory. Link to MinDat.org Location Data.

Name Origin:

Named for the locality.

Synonym:

Crestmoreite-mixture with wilkeite

Tobermorite Image

Images:

Tobermorite

Comments: Bright white tobermorite with blue calcite, USA.
Location: Crestmore Quarry, Riverside County, California. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Tobermorite Crystallography

Axial Ratios:

a:b:c =1.5416:1:3.0832

Cell Dimensions:

a = 11.3, b = 7.33, c = 22.6, Z = 4; V = 1,871.94 Den(Calc)= 2.49

Crystal System:

Orthorhombic - DisphenoidalH-M Symbol (2 2 2) Space Group: C 222₁

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

By Intensity(I/I_o): 14(1), 3.706(0.65), 3.001(0.45),1.835(0.35), 2.812(0.3), 5.5(0.25), 2.793(0.13),

Crystal Structure:

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Merlino S , Bonaccorsi E , Armbruster T , American Mineralogist , 84 (1999) p.1613-1621, Tobermorites: Their real structure and order-disorder (OD) character, Sample: 9 Angstrom

View Additional jPOWD Structure files for Tobermorite
[1] [2] [3] [4] [5] [6]

Physical Properties of Tobermorite

Cleavage:

[001] Perfect, [100] Imperfect

Color:

White, Light pink white, Reddish white.

Density:

2.423 - 2.44, Average = 2.43

Diaphaniety:

Translucent

Habit:

Aggregates - Made of numerous individual crystals or clusters.

Habit:

Fibrous - Crystals made up of fibers.

Habit:

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

Hardness:

2.5 - Finger Nail

Luminescence:

Fluorescent.

Luster:

Silky

Streak:

white

Optical Properties of Tobermorite

Gladstone-Dale:

CI meas= -0.064 (Fair) - where the CI = (1-KPDmeas/KC)
CI calc= -0.039 (Good) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2297,KPDmeas= 0.2352,KC= 0.2211

Optical Data:

Biaxial (+), a=1.57, b=1.571, g=1.575, bire=0.0050

Pleochroism (x):

colorless.

Pleochroism (y):

colorless.

Pleochroism (z):

colorless.

Calculated Properties of Tobermorite

Electron Density:

r_electron=2.52 gm/cc
note: r_Tobermorite=2.49 gm/cc.

Fermion Index

Fermion Index = 0.01084
Boson Index = 0.98916

Photoelectric:

PE_Tobermorite= 3.91 barns/electron
U=PE_Tobermorite x r_electron= 9.86 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Tobermorite is Not Radioactive

Tobermorite Classification

Dana Class:

72.3.2.1 (72)Phyllosilicate Two-Dimensional Infinite Sheets with Other Than Six-Membered Rings

(72.3)with 3-, 4-, or 5-membered rings and 8-membered rings

(72.3.2)Tobermorite group (5- & 8-membered rings)

72.3.2.1 Tobermorite Ca5Si6O16(OH)2·4(H2O) C 222₁ 2 2 2

72.3.2.2 Clinotobermorite Ca5Si6(O,OH)18·5(H2O) Cc,C 2/c Mono

72.3.2.3 Plombierite Ca5H2Si6O18·6(H2O)(?) C 222₁ 2 2 2

72.3.2.4 Riversideite Ca5Si6O16(OH)2·2(H2O) B2212 2 2 2

72.3.2.5 Okenite Ca3[Si6O15]·6(H2O) P1 or P1 Tri

72.3.2.6 Tacharanite Ca12Al2Si18O33(OH)36 A centered Mono

72.3.2.7 Nekoite Ca3Si6O15·7(H2O) P1 1

72.3.2.8 Oyelite Ca10B2Si8O29·12(H2O) B**** Ortho

Strunz Class:

VIII/F.19-20 VIII - Silicates

VIII/F - Inosilicates (chain and band) Triplet chains [Si3O9]6-

VIII/F.19 - Riversideite - Plombierite series

VIII/F.19-10 Riversideite Ca5Si6O16(OH)2·2(H2O) B2212 2 2 2

VIII/F.19-20 Tobermorite Ca5Si6O16(OH)2·4(H2O) C 222₁ 2 2 2

VIII/F.19-25 Clinotobermorite Ca5Si6(O,OH)18·5(H2O) Cc,C 2/c Mono

VIII/F.19-30 Plombierite Ca5H2Si6O18·6(H2O)(?) C 222₁ 2 2 2

Other Tobermorite Information

References:

NAME( AntBidBlaNic2) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)

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Tobermorite

Ca5Si6O16(OH)2·4(H2O)
Dana No: 72.3.2.1 Strunz No: VIII/F.19-20
Locality:

Notes: