Ilvaite Mineral Data

Ilvaite Mineral Data +

General Ilvaite Information

Chemical Formula:

CaFe++2Fe+++Si2O7O(OH)

Composition:

Molecular Weight = 408.79 gm

Calcium 9.80 % Ca 13.72 % CaO

Iron 40.98 % Fe 52.73 % FeO

Silicon 13.74 % Si 29.40 % SiO₂

Hydrogen 0.25 % H 2.20 % H₂O

Oxygen 35.22 % O

______ ______

100.00 % 98.04 % = TOTAL OXIDE

Empirical Formula:

CaFe²⁺₃(SiO₄)₂(OH)

Environment:

Occurs with magnetite ore bodies, with zinc and copper ores, and in contact deposits and zeolites.

IMA Status:

Valid Species (Pre-IMA) 1811

Locality:

Capo Calamita, on Elba. Link to MinDat.org Location Data.

Name Origin:

Named ilvaite from the Latin name of the island of Elba.

Synonym:

Breislakite - fiberous

Lievrite

Yenite

Ilvaite Image

Images:

Ilvaite Quartz

Comments: Black, prismatic ilvaite with quartz.
Location: First Sovietskij mine, Dalnjegorsk, Russia. Scale: 3.5 x 4.5 cm.
© Fabre Minerals

Images:

Ilvaite Hedenbergite

Comments: Doubly terminated, black ilvaite on crystals of greenish gray hedenbergite with minor galena.
Location: First Sovietsky mine, Dalnjegorsk, Russia. Scale: 4 x 2.8 x 1.8 cm.
© Fabre Minerals

Ilvaite Crystallography

Axial Ratios:

a:b:c =0.6759:1:0.4503

Cell Dimensions:

a = 8.78, b = 12.99, c = 5.85, Z = 4; V = 667.21 Den(Calc)= 4.07

Crystal System:

Orthorhombic - DipyramidalH-M Symbol (2/m 2/m 2/m) Space Group: Pbnm

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

By Intensity(I/I_o): 2.709(1), 2.839(0.85), 7.28(0.7),

Forms:

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Forms: [ 1 0 1] [ 0 1 0] [ 1 1 0] [ 1 1 1] [ 1 2 0]

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Crystal Structure:

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Ghose S , Sen Gupta P K , Schlemper E O , American Mineralogist , 70 (1985) p.1248-1252, Electron ordering in ilvaite, a mixed-valence iron, silicate: crystal structure refinement at 138 K, Sample: T = 138 K

View Additional jPOWD Structure files for Ilvaite
[1] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [2] [20] [21] [22] [23] [24] [25] [26] [27] [28] [29] [3] [30] [31] [32] [33] [34] [35] [36] [37] [4] [5] [6] [7] [8] [9]

Physical Properties of Ilvaite

Cleavage:

[010] Distinct, [001] Distinct

Color:

Iron black, Dark grayish black.

Density:

3.99 - 4.05, Average = 4.01

Diaphaniety:

Opaque

Fracture:

Uneven - Flat surfaces (not cleavage) fractured in an uneven pattern.

Habit:

Columnar - Forms columns

Habit:

Massive - Uniformly indistinguishable crystals forming large masses.

Habit:

Striated - Parallel lines on crystal surface or cleavage face.

Hardness:

5.5-6 - Knife Blade-Orthoclase

Luminescence:

None.

Luster:

Sub Metallic

Streak:

brownish black

Optical Properties of Ilvaite

Gladstone-Dale:

CI meas= -0.046 (Good) - where the CI = (1-KPDmeas/KC)
CI calc= -0.033 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2031,KPDmeas= 0.2056,KC= 0.1966

Optical Data:

Biaxial (-), a=1.727, b=1.87, g=1.883, bire=0.1560, 2V(Calc)=30, 2V(Meas)=20-30. Dispersion strong, r < v.

Calculated Properties of Ilvaite

Electron Density:

r_electron=3.96 gm/cc
note: r_Ilvaite=4.07 gm/cc.

Fermion Index

Fermion Index = 0.0154
Boson Index = 0.9846

Photoelectric:

PE_Ilvaite= 14.01 barns/electron
U=PE_Ilvaite x r_electron= 55.51 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Ilvaite is Not Radioactive

Ilvaite Classification

Dana Class:

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

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

(56.2.3)Lawsonite - Ilvaite group

56.2.3.1 Lawsonite CaAl2Si2O7(OH)2·(H2O) Ccmm 2/m 2/m 2/m

56.2.3.2 Hennomartinite SrMn2Si2O7(OH)2·(H2O) C mcm 2/m 2/m 2/m

56.2.3.3 Ilvaite CaFe2FeSi2O7O(OH) Pbnm 2/m 2/m 2/m

56.2.3.4 Noelbensonite! BaMn2(Si2O7)(OH)2·(H2O) C mcm 2/m 2/m 2/m

56.2.3.5 Itoigawaite! SrAl2Si2O7(OH)2·(H2O) C mcm 2/m 2/m 2/m

56.2.3.6 IMA2002-016! CaFeFe(Mn,Fe)(Si2O7)O(OH) P 2₁/a 2/m

Strunz Class:

VIII/C.10-20 VIII - Silicates

VIII/C - Sorosilicates with [Si2O7]6-, with anions unfamiliar to tetraheders [O,OH,F]

VIII/C.10 - Lawsonite - Ilvaite series

VIII/C.10-10 Lawsonite CaAl2Si2O7(OH)2·(H2O) Ccmm 2/m 2/m 2/m

VIII/C.10-12 Itoigawaite! SrAl2Si2O7(OH)2·(H2O) C mcm 2/m 2/m 2/m

VIII/C.10-15 Hennomartinite SrMn2Si2O7(OH)2·(H2O) C mcm 2/m 2/m 2/m

VIII/C.10-17 Noelbensonite! BaMn2(Si2O7)(OH)2·(H2O) C mcm 2/m 2/m 2/m

VIII/C.10-20 Ilvaite CaFe2FeSi2O7O(OH) Pbnm 2/m 2/m 2/m

Other Ilvaite Information

References:

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

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Ilvaite

CaFe++2Fe+++Si2O7O(OH)
Dana No: 56.2.3.3 Strunz No: VIII/C.10-20
Locality:

Notes: