Tilleyite Mineral Data

General Tilleyite Information

Chemical Formula:

Ca5Si2O7(CO3)2

Composition:

Molecular Weight = 488.58 gm

Calcium 41.02 % Ca 57.39 % CaO

Silicon 11.50 % Si 24.60 % SiO₂

Carbon 4.92 % C 18.02 % CO₂

Oxygen 42.57 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Ca₅Si₂O₇(CO₃)₂

Environment:

In the contact metamorphic zone between igneous rocks and limestones, formed at low pressure and high temperature.

IMA Status:

Valid Species (Pre-IMA) 1933

Locality:

Crestmore quarry, 5 miles NW of Riverside, Riverside County, California. Link to MinDat.org Location Data.

Name Origin:

Named for Cecil Edgar Tilley (1894-1973), British petrologist, Cambridge University, Cambridge, England.

Name Pronunciation:

Tilleyite + Pronunciation

Synonym:

ICSD 14256

PDF 24-184

Tilleyite Image

Images:

Tilleyite

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

Tilleyite Crystallography

Axial Ratios:

a:b:c =1.4631:1:0.7428

Cell Dimensions:

a = 15.025, b = 10.269, c = 7.628, Z = 4; beta = 105.833° V = 1,132.29 Den(Calc)= 2.87

Crystal System:

Monoclinic - Prismatic H-M Symbol (2/m) Space Group: P 2₁/a

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

By Intensity(I/I_o): 3.005(1), 3.095(0.85), 2.895(0.65),

Physical Properties of Tilleyite

Cleavage:

{100} Perfect, {101} Good

Color:

Colorless, White.

Density:

2.84

Diaphaneity:

Transparent to Translucent

Streak:

white

Optical Properties of Tilleyite

Gladstone-Dale:

CI meas= -0.064 (Fair) - where the CI = (1-KPDmeas/KC)
CI calc= -0.053 (Good) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2208,KPDmeas= 0.2231,KC= 0.2097
Ncalc = 1.6

Optical Data:

Biaxial (+), a=1.612-1.617, b=1.632-1.635, g=1.652-1.654, bire=0.0370-0.0400, 2V(Calc)=88-90, 2V(Meas)=85-90. Dispersion r < v.

Calculated Properties of Tilleyite

Electron Density:

Bulk Density (Electron Density)=2.87 gm/cc
note: Specific Gravity of Tilleyite =2.87 gm/cc.

Fermion Index:

Fermion Index = 0.0066679407
Boson Index = 0.9933320593

Photoelectric:

PE_Tilleyite= 5.53 barns/electron
U=PE_Tilleyite x rElectron Density= 15.84 barns/cc.

Radioactivity:

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

Tilleyite Classification

Dana Class:

56.02.09.01 (56)Sorosilicate Si2O7 Groups and O, OH, F. and H2O

(56.02)with cations in [4] and/or >[4] coordination

(56.02.09)Tilleyite - Killalaite group

56.02.09.01 Tilleyite Ca5Si2O7(CO3)2 P 2₁/a 2/m

56.02.09.02 Killalaite 2Ca3Si2O7•(H2O) P 2₁/m 2/m

56.02.09.03 Foshallasite? Ca3Si2O7•3(H2O) Mono

Strunz Class:

09.BE.08.2 09 - SILICATES (Germanates)

09.B - Sorosilicates

09.BE -Si2O7 groups with additional anions;

09.BE.08.2 Tilleyite Ca5Si2O7(CO3)2 P 2₁/a 2/m

Other Tilleyite Information

References:

NAME( AntBidBlaNic2) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Heinrich65)

See Also:

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

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Print or Cut-and-Paste your Tilleyite Specimen Label here :

Tilleyite

Ca5Si2O7(CO3)2
Dana No: 56.02.09.01 Strunz No: 09.BE.08.2
Locality:

Notes:

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