Afwillite Mineral Data

Afwillite Mineral Data +

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General Afwillite Information

Chemical Formula:

Ca3Si2O4(OH)6

Composition:

Molecular Weight = 342.45 gm

Calcium 35.11 % Ca 49.13 % CaO

Silicon 16.40 % Si 35.09 % SiO₂

Hydrogen 1.77 % H 15.78 % H₂O

Oxygen 46.72 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Ca₃(Si₂O₄)(OH)₆

Environment:

A product of contact metamorphism of limestones.

IMA Status:

Valid Species (Pre-IMA) 1925

Locality:

From the Dutoitspan diamond mine, Kimberley, and the Wessels mine, near Kuruman, Cape Province, South Africa. Link to MinDat.org Location Data.

Name Origin:

For Alpheus Fuller Williams (1874-1953), General Manager, DeBeers Consolidated Mines, Kimberley, South Africa.

Synonym:

ICSD 18

PDF 29-330

Afwillite Image

Images:

Afwillite

Comments: Crystallized afwillite prisms.
Location: Wessels Mine, Kalahari Manganese Field, Northern Cape Province, South Africa. Scale: Crystal size 1.5 mm.
© John Veevaert

Afwillite Crystallography

Axial Ratios:

a:b:c =2.0822:1:2.393

Cell Dimensions:

a = 11.39, b = 5.47, c = 13.09, Z = 4; beta = 98.433° V = 806.73 Den(Calc)= 2.82

Crystal System:

Monoclinic - SphenoidalH-M Symbol (2) Space Group: P 2₁

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

By Intensity(I/I_o): 2.83(1), 3.18(0.9), 6.61(0.9),

Crystal Structure:

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Megaw H D , Acta Crystallographica , 5 (1952) p.477-491, The structure of afwillite, Ca3(SiO3OH)2*2H2O, Locality: Scawt Hill, Northern Ireland

View Additional jPOWD Structure files for Afwillite
[1]

Physical Properties of Afwillite

Cleavage:

[001] Perfect, [???] Distinct

Color:

Colorless, White.

Density:

2.62

Diaphaniety:

Transparent to Subtransparent to translucent

Habit:

Massive - Uniformly indistinguishable crystals forming large masses.

Habit:

Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline).

Hardness:

3 - Calcite

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Afwillite

Gladstone-Dale:

CI meas= -0.036 (Excellent) - where the CI = (1-KPDmeas/KC)
CI calc= 0.038 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2211,KPDmeas= 0.238,KC= 0.2298

Optical Data:

Biaxial (+), a=1.6169, b=1.6204, g=1.6336, bire=0.0167

Calculated Properties of Afwillite

Electron Density:

r_electron=2.66 gm/cc
note: r_Afwillite=2.62 gm/cc.

Fermion Index

Fermion Index = 0.00836
Boson Index = 0.99164

Photoelectric:

PE_Afwillite= 4.90 barns/electron
U=PE_Afwillite x r_electron= 13.06 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Afwillite is Not Radioactive

Afwillite Classification

Dana Class:

52.4.7.1 (52)Nesosilicate Insular SiO4 Groups and O, OH, F, and H2O

(52.4)with cations in [6] and/or > [6] coordination

(52.4.7)Afwillite and related species

52.4.7.1 Afwillite Ca3Si2O4(OH)6 P 2₁ 2

52.4.7.2 Bultfonteinite Ca2SiO2(OH,F)4 P1 1

52.4.7.3 Hatrurite Ca3SiO5 R 3m 3m

52.4.7.4 Jasmundite Ca11(SiO4)4O2S I 42m 4 2m

Strunz Class:

VIII/B.22-30 VIII - Silicates

VIII/B - Nesosubsilicates, with anions unfamiliar to tetraheders, cationes with coordinationnumber between [8] and [12]

VIII/B.22 - Thaumasite series

VIII/B.22-10 Hatrurite Ca3SiO5 R 3m 3m

VIII/B.22-25 Poldervaartite (Ca,Mn)2SiO3(OH)2 P bca 2/m 2/m 2/m

VIII/B.22-30 Afwillite Ca3Si2O4(OH)6 P 2₁ 2

VIII/B.22-40 Bultfonteinite Ca2SiO2(OH,F)4 P1 1

VIII/B.22-50 Spurrite Ca5(SiO4)2(CO3) P 2₁/a 2/m

VIII/B.22-60 Paraspurrite Ca5(SiO4)2(CO3) P 2₁/a 2/m

VIII/B.22-65 Ternesite! Ca5(SiO4)2SO4 P nma 2/m 2/m 2/m

VIII/B.22-70 Nagelschmidtite Ca7(SiO4)3(PO4)2 Unk Hex

VIII/B.22-75 Harrisonite! Ca(Fe,Mg)6(PO4)2(SiO4)2 R 3m 3 2/m

VIII/B.22-80 Fukalite Ca4Si2O6(CO3)(OH,F)2 Unk Ortho

VIII/B.22-90 Thaumasite Ca3Si(CO3)(SO4)(OH)6·12(H2O) P 6₃/m 6/m

VIII/B.22-100 Chelyabinskite* (Ca,Mg)3Si(OH)6(SO4,CO3)2·9(H2O) Unk Ortho

Other Afwillite Information

References:

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

See Also:

Links to other databases for Afwillite :
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
15 - WWW-MINCRYST

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

Afwillite

Ca3Si2O4(OH)6
Dana No: 52.4.7.1 Strunz No: VIII/B.22-30
Locality:

Notes: