Virgilite Mineral Data
General Virgilite Information
Chemical Formula:
LixAlxSi3-xO6
Composition:
Molecular Weight = 183.17 gm
Lithium 1.89 % Li 4.08 % Li2 O
Aluminum 7.37 % Al 13.92 % Al2 O3
Silicon 38.33 % Si 82.01 % SiO2
Oxygen 52.41 % O
______ ______
100.00 % 100.00 % = TOTAL OXIDE
Empirical Formula:
Li0.5 Al0.5 Si2.5 O6
Environment:
As inclusions in stream cobbles of peraluminous volcanic glass.
IMA Status:
Approved IMA 1978
Locality:
From near Macusani, Puno Department, Peru. Link to MinDat.org Location Data.
Name Origin:
Named for Virgil Everett Barnes (1903-), University of Texas, Austin, Texas, USA, prominent worker on tektites, impactites, and other natural glasses.
Name Pronunciation:
Virgilite + Pronunciation
Synonym:
ICSD 69221
PDF 31-707
Virgilite Image
Images:
Virgilite
Comments: B&W image of euhedral virgilite crystal surrounded by glass containing several other virgilite crystals. Plane polarized light. AmMin v63:461.
Location: Clear pale-green glass found as stream cobbles near Macusani, Peru.
Scale: Crystal Size 40 µm.
© American Mineralogist
Virgilite Crystallography
Axial Ratios:
a:c = 1:1.06274
Cell Dimensions:
a = 5.132, c = 5.454, Z = 1; V = 124.40 Den(Calc)= 2.44
Crystal System:
Hexagonal - Trapezohedral H-M Symbol (6 2 2) Space Group: P 62 22,P 64 22
X Ray Diffraction:
By Intensity(I/Io ): 3.441(1), 1.87(0.25), 4.442(0.13),
Physical Properties of Virgilite
Color:
Colorless.
Density:
2.46
Diaphaneity:
Transparent
Habit:
Inclusions - Generally found as inclusions in other minerals.
Hardness:
5.5-6 - Knife Blade-Orthoclase
Streak:
white
Optical Properties of Virgilite
Gladstone-Dale:
CI meas = 0.002 (Superior) - where the CI = (1-KPDmeas /KC ) CI calc = -0.006 (Superior) - where the CI = (1-KPDcalc /KC )
KPDcalc = 0.2131,KPDmeas = 0.2114,KC = 0.2119 Ncalc = 1.52
Optical Data:
Uniaxial (-), w=1.52.
Calculated Properties of Virgilite
Electron Density:
Bulk Density (Electron Density)=2.44 gm/cc note: Specific Gravity of Virgilite =2.46 gm/cc.
Fermion Index:
Fermion Index = 0.01 Boson Index = 0.99
Photoelectric:
PEVirgilite = 1.70 barns/electronU=PEVirgilite x r Electron Density= 4.16 barns/cc.
Radioactivity:
GRapi = 0 (Gamma Ray American Petroleum Institute Units) Virgilite is Not Radioactive
Virgilite Classification
Dana Class:
75.03.01.01 (75) Tectosilicate Si Tetrahedral Frameworks
(75.03) with silica derivative structures
(75.03.01) Dana Group
75.03.01.01 Virgilite LixAlxSi3-xO6 P 62 22,P 64 22 6 2 2
Strunz Class:
09.FA.15 09 - SILICATES (Germanates)
09.F - Tektosilicates without Zeolitic H2O
09.FA -Tektosilicates without additional non-tetrahedral anions, (Al,B):Si = 1:1
09.FA.15 Virgilite LixAlxSi3-xO6 P 62 22,P 64 22 6 2 2
Other Virgilite 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 Virgilite :
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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Virgilite
LixAlxSi3-xO6
Dana No: 75.03.01.01 Strunz No: 09.FA.15
Locality:
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