Petalite Mineral Data

Petalite Mineral Data +

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General Petalite Information

Chemical Formula:

LiAlSi4O10

Composition:

Molecular Weight = 305.15 gm

Lithium 2.09 % Li 4.50 % Li₂O

Aluminum 8.75 % Al 16.54 % Al₂O₃

Silicon 36.72 % Si 78.56 % SiO₂

Oxygen 52.43 % O

______ ______

100.00 % 99.61 % = TOTAL OXIDE

Empirical Formula:

Li_0.92Al_0.99Si_3.99O₁₀

Environment:

In granite pegmatites, locally constituting an ore of lithium.

IMA Status:

Valid Species (Pre-IMA) 1800

Locality:

Mining Academy, Freiberg, Germany, Link to MinDat.org Location Data.

Name Origin:

From the Greek petalon - "leaf" in allusion to the perfect basal cleavage.

Synonym:

ICSD 100348

PDF 35-463

Petalite Image

Images:

Petalite

Comments: Translucent, gemmy , equant petalite crystal with an etched surface texture resulting in irregular faces.
Location: Paprok, Konar (Kunar; Konarh; Konarha; Nuristan) Province, Afghanistan. Scale: 5x3.5x3 cm.
© John Betts - Fine Minerals

Petalite Crystallography

Axial Ratios:

a:b:c =2.2869:1:1.4845

Cell Dimensions:

a = 11.754, b = 5.1395, c = 7.6296, Z = 2; beta = 113.04° V = 424.14 Den(Calc)= 2.39

Crystal System:

Monoclinic - PrismaticH-M Symbol (2/m) Space Group: P 2/a

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

By Intensity(I/I_o): 3.7255(1), 3.7341(0.95), 3.6734(0.75),

Crystal Structure:

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Tagai T , Ried H , Joswig W , Korekawa M , Zeitschrift fur Kristallographie , 160 (1982) p.159-170, Kristallographische untersuchungen eines petalits mittels neutronenbeugung und, transmissionselektronenmikroskopie, Locality: Varutrask, Sweden

Physical Properties of Petalite

Cleavage:

[001] Perfect, [???] Imperfect

Color:

Colorless, Gray, Yellow, Yellow gray, White.

Density:

2.39 - 2.46, Average = 2.42

Diaphaniety:

Transparent to translucent

Fracture:

Brittle - Conchoidal - Very brittle fracture producing small, conchoidal fragments.

Habit:

Massive - Uniformly indistinguishable crystals forming large masses.

Hardness:

6-6.5 - Orthoclase-Pyrite

Luminescence:

Fluorescent.

Luster:

Vitreous - Pearly

Streak:

colorless

Optical Properties of Petalite

Gladstone-Dale:

CI meas= 0.006 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= -0.009 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2134,KPDmeas= 0.2103,KC= 0.2115

Optical Data:

Biaxial (+), a=1.504, b=1.51, g=1.516, bire=0.0120

Calculated Properties of Petalite

Electron Density:

r_electron=2.41 gm/cc
note: r_Petalite=2.43 gm/cc.

Fermion Index

Fermion Index = 0.01897
Boson Index = 0.98103

Photoelectric:

PE_Petalite= 1.69 barns/electron
U=PE_Petalite x r_electron= 4.06 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Petalite is Not Radioactive

Petalite Classification

Dana Class:

72.6.1.1 (72)Phyllosilicate Two-Dimensional Infinite Sheets with Other Than Six-Membered Rings

(72.6)with tetrahedral Al cross-linking

(72.6.1)Dana Group

72.6.1.1 Petalite LiAlSi4O10 P 2/a 2/m

Strunz Class:

VIII/J.03-10 VIII - Silicates

VIII/J - Tectosilicates (network) without anions unfamiliar to the tetraheders

VIII/J.03 - Petalite - Virgilite series

VIII/J.03-10 Petalite LiAlSi4O10 P 2/a 2/m

VIII/J.03-20 Virgilite LixAlxSi3-xO6 P 6₂22,P 6₄22 6 2 2

VIII/J.03-30 Lisitsynite! KBSi2O6 P 2₁2₁2₁ 2 2 2

Other Petalite Information

References:

NAME( AntBidBlaNic2) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Ford32)

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Petalite

LiAlSi4O10
Dana No: 72.6.1.1 Strunz No: VIII/J.03-10
Locality:

Notes: