Kegelite Mineral Data
General Kegelite Information
Chemical Formula:
Pb8Al4Si8O20(SO4)2(CO3)4(OH)8
Composition:
Molecular Weight = 2,878.42 gm
Aluminum 3.75 % Al 7.08 % Al2 O3
Silicon 7.81 % Si 16.70 % SiO2
Hydrogen 0.28 % H 2.50 % H2 O
Lead 57.59 % Pb 62.03 % PbO
Carbon 1.67 % C 6.12 % CO2
Sulfur 2.23 % S 5.56 % SO3
Oxygen 26.68 % O
______ ______
100.00 % 100.00 % = TOTAL OXIDE
Empirical Formula:
Pb8 Al4 Si8 (SO4 )2 (CO3 )4 (OH)8 O20
Environment:
Deep oxidation zone at the mine.
IMA Status:
Approved IMA 1975
Locality:
Tsumbe, Namibia. Link to MinDat.org Location Data.
Name Origin:
Named for Friedrich Wilhelm Kegel, director of the Tsumbe mine from 1922 to 1938.
Name Pronunciation:
Kegelite
Kegelite Image
Images:
Kegelite
Comments: Small, transparent pseudo-cubic kegelite crystals.
Location: Tsumbe, Namibia..
Scale: See Image.
© William Pinch
Kegelite Crystallography
Axial Ratios:
a:b:c =1.353:1:0.5778
Cell Dimensions:
a = 21.04, b = 15.55, c = 8.986, Z = 3; beta = 91° V = 2,939.52 Den(Calc)= 4.88
Crystal System:
Monoclinic Space Group: A2/m,A2,Am
X Ray Diffraction:
By Intensity(I/Io ): 21(1), 2.591(0.9), 3.82(0.8),
Physical Properties of Kegelite
Cleavage:
{???} Perfect
Color:
Colorless, Pearl white.
Density:
4.46 - 4.549, Average = 4.5
Diaphaneity:
Transparent to Translucent
Luster:
Pearly
Streak:
white
Optical Properties of Kegelite
Gladstone-Dale:
CI meas = -0.102 (Poor) - where the CI = (1-KPDmeas /KC ) CI calc = -0.017 (Superior) - where the CI = (1-KPDcalc /KC )
KPDcalc = 0.166,KPDmeas = 0.1798,KC = 0.1632 Ncalc = 1.73 - 1.8
Optical Data:
Biaxial (-), b=1.81
Calculated Properties of Kegelite
Electron Density:
Bulk Density (Electron Density)=4.30 gm/cc note: Specific Gravity of Kegelite =4.88 gm/cc.
Fermion Index:
Fermion Index = 0.13 Boson Index = 0.87
Photoelectric:
PEKegelite =1,004.03 barns/electronU=PEKegelite x r Electron Density=4,316.79 barns/cc.
Radioactivity:
GRapi = 0 (Gamma Ray American Petroleum Institute Units) Kegelite is Not Radioactive
Kegelite Classification
Dana Class:
71.05.01.01 (71) Phyllosilicate Sheets of Six-Membered Rings
(71.05) with other anions
(71.05.01) Dana Group
71.05.01.01 Kegelite Pb8Al4Si8O20(SO4)2(CO3)4(OH)8 A2/m,A2,Am Mono
Strunz Class:
09.EC.80 09 - SILICATES (Germanates)
09.E - Phyllosilicates
09.EC -Phyllosilicates with mica sheets, composed of tetrahedral and octahedral nets
09.EC.80 Kegelite Pb8Al4Si8O20(SO4)2(CO3)4(OH)8 A2/m,A2,Am Mono
Other Kegelite Information
References:
NAME( Dana8) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)
See Also:
Links to other databases for Kegelite :
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
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Kegelite
Pb8Al4Si8O20(SO4)2(CO3)4(OH)8
Dana No: 71.05.01.01 Strunz No: 09.EC.80
Locality:
Notes:
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