Virgilite Mineral Data

General Virgilite Information

Chemical Formula:

LixAlxSi3-xO6

Composition:

Molecular Weight = 183.17 gm

Lithium 1.89 % Li 4.08 % Li₂O

Aluminum 7.37 % Al 13.92 % Al₂O₃

Silicon 38.33 % Si 82.01 % SiO₂

Oxygen 52.41 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Li_0.5Al_0.5Si_2.5O₆

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 6₂22,P 6₄22

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

By Intensity(I/I_o): 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:

PE_Virgilite= 1.70 barns/electron
U=PE_Virgilite x rElectron 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 6₂22,P 6₄22 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 6₂22,P 6₄22 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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Print or Cut-and-Paste your Virgilite Specimen Label here :

Virgilite

LixAlxSi3-xO6
Dana No: 75.03.01.01 Strunz No: 09.FA.15
Locality:

Notes:

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