Afwillite Mineral Data
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 % H2 O
Oxygen 46.72 % O
______ ______
100.00 % 100.00 % = TOTAL OXIDE
Empirical Formula:
Ca3 (Si2 O4 )(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.
Name Pronunciation:
Afwillite + Pronunciation
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 - Sphenoidal H-M Symbol (2) Space Group: P 21
X Ray Diffraction:
By Intensity(I/Io ): 2.83(1), 3.18(0.9), 6.61(0.9),
Physical Properties of Afwillite
Cleavage:
{001} Perfect, {???} Distinct
Color:
Colorless, White.
Density:
2.62
Diaphaneity:
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 Ncalc = 1.6 - 1.65
Optical Data:
Biaxial (+), a=1.6169, b=1.6204, g=1.6336, bire=0.0167
Calculated Properties of Afwillite
Electron Density:
Bulk Density (Electron Density)=2.66 gm/cc note: Specific Gravity of Afwillite =2.62 gm/cc.
Fermion Index:
Fermion Index = 0.0083610278 Boson Index = 0.9916389722
Photoelectric:
PEAfwillite = 4.90 barns/electronU=PEAfwillite x r Electron Density= 13.06 barns/cc.
Radioactivity:
GRapi = 0 (Gamma Ray American Petroleum Institute Units) Afwillite is Not Radioactive
Afwillite Classification
Dana Class:
52.04.07.01 (52) Nesosilicate Insular SiO4 Groups and O, OH, F, and H2O
(52.04) with cations in [6] and/or > [6] coordination
(52.04.07) Afwillite and related species
52.04.07.01 Afwillite Ca3Si2O4(OH)6 P 21 2
52.04.07.02 Bultfonteinite Ca2SiO2(OH,F)4 P1 1
52.04.07.03 Hatrurite Ca3SiO5 R 3m 3m
52.04.07.04 Jasmundite Ca11(SiO4)4O2S I 4 2m 4 2m
Strunz Class:
09.AG.75 09 - SILICATES (Germanates)
09.A - Nesosilicates
09.AG -Nesosilicates with additional anions; cations in > [6] � [6] coordination
09.AG.75 Afwillite Ca3Si2O4(OH)6 P 21 2
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 - GeoScienceWorld
6 - Google Images
7 - Google Scholar
8 - Handbook of Mineralogy (MinSocAm)
9 - Handbook of Mineralogy (UofA)
10 - MinDAT
11 - Mineralienatlas (Deutsch)
12 - Online Mineral Museum
13 - QUT Mineral Atlas
14 - Ruff.Info
15 - WWW-MINCRYST
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Afwillite
Ca3Si2O4(OH)6
Dana No: 52.04.07.01 Strunz No: 09.AG.75
Locality:
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