Yofortierite Mineral Data

Yofortierite Mineral Data

General Yofortierite Information

Chemical Formula:

(Mn,Mg)5Si8O20(OH)2·8-9(H2O)

Composition:

Molecular Weight = 1,002.61 gm

Calcium 0.80 % Ca 1.12 % CaO

Magnesium 1.45 % Mg 2.41 % MgO

Manganese 21.92 % Mn 28.30 % MnO

Aluminum 0.81 % Al 1.53 % Al₂O₃

Zinc 0.65 % Zn 0.81 % ZnO

Silicon 22.41 % Si 47.94 % SiO₂

Hydrogen 2.01 % H 17.97 % H₂O

Oxygen 49.95 % O

______ ______

100.00 % 100.08 % = TOTAL OXIDE

Empirical Formula:

Mn²⁺₄Mg_0.6Al_0.3Ca_0.2Zn_0.1Si₈O_20.3(OH)₂·9(H₂O)

Environment:

Late stage hydrothermal mineral in pegmatite veins within nepheline syenite.

IMA Status:

Approved IMA 1975

Locality:

Mont Saint-Hilaire, Quebec, Canada. Link to MinDat.org Location Data.

Name Origin:

Named for Yves Oscar Fortier (1914-), formater Director of the Geological Survey of Canada (1964-1972).

Synonym:

IMA1974-045

Yofortierite Image

Images:

Yofortierite

Comments: Radial spray of yofortierite in matrix.
Location: Mt. St. Hilaire, Quebec, Canada. Scale: Picture size 1.5 cm.
© John Veevaert

Yofortierite Crystallography

Axial Ratios:

a:b:c =0.6945:1:0.2735

Cell Dimensions:

a = 12.759, b = 18.369, c = 5.024, Z = 2; beta = 94.98° V = 1,173.03 Den(Calc)= 2.84

Crystal System:

Monoclinic - DomaticH-M Symbol (m) Space Group: Pn(?)

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

By Intensity(I/I_o): 10.5(1), 3.302(0.9), 2.621(0.3),

Physical Properties of Yofortierite

Color:

Violet brown, Light violet, Pink.

Density:

2.18

Diaphaniety:

Transparent

Fracture:

Elastic - Fragments which spring back after bending.

Habit:

Acicular - Occurs as needle-like crystals.

Habit:

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

Hardness:

2.5 - Finger Nail

Streak:

light pink

Optical Properties of Yofortierite

Gladstone-Dale:

CI meas= -0.095 (Poor) - where the CI = (1-KPDmeas/KC)
CI calc= 0.16 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1917,KPDmeas= 0.2498,KC= 0.2282

Optical Data:

Biaxial (?), a=1.53, g=1.559, bire=0.0290

Pleochroism (x):

distinct.

Pleochroism (y):

distinct.

Pleochroism (z):

distinct.

Calculated Properties of Yofortierite

Electron Density:

r_electron=2.18 gm/cc
note: r_Yofortierite=2.18 gm/cc.

Fermion Index

Fermion Index = 0.01244
Boson Index = 0.98756

Photoelectric:

PE_Yofortierite= 6.81 barns/electron
U=PE_Yofortierite x r_electron= 14.82 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Yofortierite is Not Radioactive

Yofortierite Classification

Dana Class:

74.3.1a.3 (74)Phyllosilicate Modulated Layers

(74.3)with joined strips

(74.3.1a)Palygorskite-sepiolite group (Palygorskite subgroup)

74.3.1a.1 Palygorskite (Mg,Al)2Si4O10(OH)·4(H2O) C 2/m 2/m

74.3.1a.2 Tuperssuatsiaite Na(Fe,Mn)3[Si8O20](OH)2·n(H2O) C 2/m Mono

74.3.1a.3 Yofortierite (Mn,Mg)5Si8O20(OH)2·8-9(H2O) Pn(?) m

74.3.1a.4 Kalifersite! (K,Na)5Fe7Si20O50(OH)6·12(H2O) P1 1

Strunz Class:

VIII/H.33-30 VIII - Silicates

VIII/H - Phyllosilicates (layered) Mica minerals with other simple layers, [Si6O15]6- and others

VIII/H.33 - Tuperssuatsiaite - Loughlinite series

VIII/H.33-10 Tuperssuatsiaite Na(Fe,Mn)3[Si8O20](OH)2·n(H2O) C 2/m Mono

VIII/H.33-20 Palygorskite (Mg,Al)2Si4O10(OH)·4(H2O) C 2/m 2/m

VIII/H.33-30 Yofortierite (Mn,Mg)5Si8O20(OH)2·8-9(H2O) Pn(?) m

VIII/H.33-40 Sepiolite Mg4Si6O15(OH)2·6(H2O) Pnan 2/m 2/m 2/m

VIII/H.33-50 Falcondoite (Ni,Mg)4Si6O15(OH)2·6(H2O) Pncn 2/m 2/m 2/m

VIII/H.33-60 Loughlinite Na2Mg3Si6O16·8(H2O) Unk Ortho

VIII/H.33-80 Intersilite! Na6MnTi[Si10O24(OH)](OH)3·4(H2O) I2/m 2/m

VIII/H.33-90 Kalifersite! (K,Na)5Fe7Si20O50(OH)6·12(H2O) P1 1

Other Yofortierite Information

References:

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

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Yofortierite

(Mn,Mg)5Si8O20(OH)2·8-9(H2O)
Dana No: 74.3.1a.3 Strunz No: VIII/H.33-30
Locality:

Notes: