Silvialite Mineral Data

Silvialite Mineral Data

General Silvialite Information

Chemical Formula:

(Ca,Na)4Al6Si6O24(SO4,CO3)

Composition:

Molecular Weight = 939.25 gm

Sodium 2.45 % Na 3.30 % Na₂O

Calcium 12.80 % Ca 17.91 % CaO

Aluminum 17.24 % Al 32.57 % Al₂O₃

Silicon 17.94 % Si 38.38 % SiO₂

Carbon 0.51 % C 1.87 % CO₂

Sulfur 2.05 % S 5.11 % SO₃

Oxygen 47.01 % O

______ ______

100.00 % 99.15 % = TOTAL OXIDE

Empirical Formula:

Ca₃NaAl₆Si₆O₂₄(SO₄)_0.6(CO₃)_0.4

Environment:

Garnet-granulite mantle-derived xenolith in olivine nephelinite. A member of the scapolite group.

IMA Status:

Approved IMA 1999 (Dana # Added)

Locality:

McBride Province, North Queensland, Australia. Link to MinDat.org Location Data.

Name Origin:

Named for Silvia Hillebrand, daughter of G. Tschermak, was first suggested in 1914 for the then-hypothetical SO4 analog of meionite.

Synonym:

ICSD 88935

IMA1998-010

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Silvialite Crystallography

Axial Ratios:

a:c = 1:0.62436

Cell Dimensions:

a = 12.134, c = 7.576, Z = 2; V = 1,115.44 Den(Calc)= 2.80

Crystal System:

Tetragonal - DipyramidalH-M Symbol (4/m) Space Group: I 4/m

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

By Intensity(I/I_o): 3.45(1), 3.07(0.4), 3.82(0.2),2.69(0.15), 3.04(0.15),

Physical Properties of Silvialite

Cleavage:

[100] Good

Color:

Slightly yellowish white, Colorless.

Density:

2.75

Diaphaniety:

Transparent

Fracture:

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

Habit:

Granular - Generally occurs as anhedral to subhedral crystals in matrix.

Habit:

Subhedral Crystals - Occurs as crystals which tend to exhibit a recognizable crystal shape.

Hardness:

5.5 - Knife Blade

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Silvialite

Gladstone-Dale:

CI meas= -0.018 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= 0 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2041,KPDmeas= 0.2078,KC= 0.2041

Optical Data:

Uniaxial (-), e=1.558, w=1.585, bire=0.0270.

Calculated Properties of Silvialite

Electron Density:

r_electron=2.78 gm/cc
note: r_Silvialite=2.80 gm/cc.

Fermion Index

Fermion Index = 0.00898
Boson Index = 0.99102

Photoelectric:

PE_Silvialite= 2.94 barns/electron
U=PE_Silvialite x r_electron= 8.17 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Silvialite is Not Radioactive

Silvialite Classification

Dana Class:

76.3.1.3 (76)Tectosilicate Al-Si Framework

(76.3)with other Be/Al/Si frameworks

(76.3.1)Scapolite group

76.3.1.0 Scapolite* (Na,Ca)4[Al3Si9O24]Cl P 4₁/n 4/m

76.3.1.1 Marialite Na4Al3Si9O24Cl I 4/m 4/m

76.3.1.2 Meionite Ca4Al6Si6O24CO3 P 4/m 4/m

76.3.1.3 Silvialite ! (Ca,Na)4Al6Si6O24(SO4,CO3) I 4/m 4/m

Strunz Class:

VIII/J.13-25 VIII - Silicates

VIII/J - Tectosilicates (network) with anions unfamiliar to the tetraheders

VIII/J.13 - Sodalite group, Marialite - Kalborsite series

VIII/J.13-10 Marialite Na4Al3Si9O24Cl I 4/m 4/m

VIII/J.13-20 Meionite Ca4Al6Si6O24CO3 P 4/m 4/m

VIII/J.13-25 Silvialite (Ca,Na)4Al6Si6O24(SO4,CO3) I 4/m 4/m

VIII/J.13-30 Sarcolite NaCa6Al4Si6O24F(?) I 4/m 4/m

VIII/J.13-40 Kalborsite K6Al4Si6BO20(OH)4Cl P 42m 4 2m

Other Silvialite Information

References:

NAME( AmMin, V85, p264) PHYS. PROP.(AmMin, V85, p264) OPTIC PROP.(AmMin, V85, p264)

See Also:

Links to other databases for Silvialite :
1 -Am. Min. Crystal Structure Database 2 -Athena 3 - Crocoite.com Mineral Locations 4 -Google Images 5 -Google Scholar 6 -MinDAT 7 -MinMax(Deutsch) 8 -MinMax(English) 9 -Mineralienatlas (Deutsch) 10 -QUT Mineral Atlas

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Silvialite

(Ca,Na)4Al6Si6O24(SO4,CO3)
Dana No: 76.3.1.3 Strunz No: VIII/J.13-25
Locality:

Notes: