Willemseite Mineral Data

Willemseite Mineral Data +

General Willemseite Information

Chemical Formula:

(Ni,Mg)3Si4O10(OH)2

Composition:

Molecular Weight = 456.63 gm

Magnesium 3.99 % Mg 6.62 % MgO

Silicon 24.60 % Si 52.63 % SiO₂

Nickel 28.92 % Ni 36.80 % NiO

Hydrogen 0.44 % H 3.95 % H₂O

Oxygen 42.05 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Ni_2.25Mg_0.75Si₄O₁₀(OH)₂

IMA Status:

Approved IMA 1970

Locality:

Link to MinDat.org Location Data.

Willemseite Image

Images:

Willemseite Trevorite

Comments: Small trevorite crystal in massive willemseite.
Location: Bon Accord, Barberton Mountain, Mpumalanga, South Africa. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Images:

Willemseite Trevorite

Comments: Waxy translucent green willemseite with black trevorite in schistose rock.
Location: Near Scotia Talc Mine, Barberton Mountain, Transvaal, Mpumalanga, South Africa. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Willemseite Crystallography

Axial Ratios:

a:b:c =0.581:1:2.076

Cell Dimensions:

a = 5.316, b = 9.149, c = 18.994, Z = 4; beta = 99.96° V = 909.87 Den(Calc)= 3.33

Crystal System:

Monoclinic - PrismaticH-M Symbol (2/m) Space Group: C 2/c

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

By Intensity(I/I_o): 9.4(1), 3.12(0.28), 2.503(0.23),

Physical Properties of Willemseite

Cleavage:

[001] Perfect

Color:

Light green.

Density:

3.31

Hardness:

2 - Gypsum

Streak:

greenish white

Optical Properties of Willemseite

Gladstone-Dale:

CI meas= 0.044 (Good) - where the CI = (1-KPDmeas/KC)
CI calc= 0.05 (Good) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1909,KPDmeas= 0.192,KC= 0.2009

Optical Data:

Biaxial (-), a=1.6, b=1.652, g=1.655, bire=0.0550, 2V(Calc)=26, 2V(Meas)=27.

Calculated Properties of Willemseite

Electron Density:

r_electron=3.28 gm/cc
note: r_Willemseite=3.31 gm/cc.

Fermion Index

Fermion Index = 0.01895
Boson Index = 0.98105

Photoelectric:

PE_Willemseite= 12.39 barns/electron
U=PE_Willemseite x r_electron= 40.60 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Willemseite is Not Radioactive

Willemseite Classification

Dana Class:

71.2.1.4 (71)Phyllosilicate Sheets of Six-Membered Rings

(71.2)with 2:1 Layers

(71.2.1)Pyrophyllite-talc group

71.2.1.1 Pyrophyllite Al2Si4O10(OH)2 P1 1

71.2.1.2 Ferripyrophyllite Fe2Si4O10(OH)2 C 2/m 2/m

71.2.1.3 Talc Mg3Si4O10(OH)2 C 2/c 2/m

71.2.1.4 Willemseite (Ni,Mg)3Si4O10(OH)2 C 2/c 2/m

71.2.1.5 Minnesotaite (Fe,Mg)3Si4O10(OH)2 C1 1

71.2.1.6 Brinrobertsite! (Na,K,Ca)x(Al,Fe,Mg)4(Si,Al)8O20(OH)4·3.54(H2O)[x=0.35,n=3.54] pseudo 2/m 2/m

Strunz Class:

VIII/H.09-60 VIII - Silicates

VIII/H - Phyllosilicates (layered) Mica like layered silicates with [Si4O10]4- and related groups

VIII/H.09 - Talc series

VIII/H.09-10 Pyrophyllite Al2Si4O10(OH)2 P1 1

VIII/H.09-20 Ferripyrophyllite Fe2Si4O10(OH)2 C 2/m 2/m

VIII/H.09-30 Macaulayite (Fe,Al)24Si4O43(OH)2 C? Mono

VIII/H.09-40 Talc Mg3Si4O10(OH)2 C 2/c 2/m

VIII/H.09-50 Minnesotaite (Fe,Mg)3Si4O10(OH)2 C1 1

VIII/H.09-60 Willemseite (Ni,Mg)3Si4O10(OH)2 C 2/c 2/m

VIII/H.09-65 Pimelite Ni3Si4O10(OH)2·4(H2O) Unk. Hex

VIII/H.09-70 Kegelite Pb8Al4Si8O20(SO4)2(CO3)4(OH)8 A2/m,A2,Am Mono

Other Willemseite Information

References:

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

See Also:

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

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Willemseite

(Ni,Mg)3Si4O10(OH)2
Dana No: 71.2.1.4 Strunz No: VIII/H.09-60
Locality:

Notes: