Lepidolite Mineral Data

General Lepidolite Information

Chemical Formula:

K(Li,Al)3(Si,Al)4O10(F,OH)2

Composition:

Molecular Weight = 388.30 gm

Potassium 10.07 % K 12.13 % K₂O

Lithium 3.58 % Li 7.70 % Li₂O

Aluminum 6.95 % Al 13.13 % Al₂O₃

Silicon 28.93 % Si 61.89 % SiO₂

Hydrogen 0.26 % H 2.32 % H₂O

Oxygen 45.32 % O

Fluorine 4.89 % F 4.89 % F

- % F -2.06 % -O=F₂

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

KLi₂AlSi₄O₁₀F(OH)

Environment:

Lithia-bearing pegmatites.

IMA Status:

Valid Species (Pre-IMA) 1792

Locality:

Pala, San Diego Co., California, USA. Link to MinDat.org Location Data.

Name Origin:

From the Greek lepidion - "scale" and lithos - "stone."

Name Pronunciation:

Lepidolite + Pronunciation

Synonym:

Lithium Mica

Lepidolite Image

Images:

Lepidolite

Comments: Pale lavender micaceous plates of lepidolite on matrix.
Location: Minas Gerais, Brazil. Scale: Not Given.
© Lou Perloff / Photo Atlas of Minerals

Images:

Lepidolite Nanpingite

Comments: Hexagonal tabular crystals of pearly colourless lepidolite within massive white pollucite from unknown rare metal pegmatite. Nanpingite forms the outer zones of these lepidolite crystals (~30-150 µm).
Location: China. Scale: Specimen size is 3.5x3x2 cm.
© Pavel M. Kartashov

Lepidolite Crystallography

Axial Ratios:

a:b:c =0.5808:1:2.2474

Cell Dimensions:

a = 5.21, b = 8.97, c = 20.16, Z = 4; beta = 100.8° V = 925.46 Den(Calc)= 2.79

Crystal System:

MonoclinicSpace Group: C 2/m,Cm

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

By Intensity(I/I_o): 3.34(1), 4.99(0.75), 10(0.75),

Forms:

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Forms: ( 1 1 2) ( 2 2 1) ( 0 1 0) ( 0 0 1)

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Crystal Structure:

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Hendricks S B , Jefferson M E , American Mineralogist , 24 (1939) p.729-771, Polymorphism of the micas with optical measurements

View Additional jPOWD Structure files for Lepidolite
[1]

Physical Properties of Lepidolite

Cleavage:

{001} Perfect

Color:

Colorless, Gray white, Lilac, Yellowish, White.

Density:

2.8 - 2.9, Average = 2.84

Diaphaneity:

Translucent

Fracture:

Uneven - Flat surfaces (not cleavage) fractured in an uneven pattern.

Habit:

Foliated - Two dimensional platy forms.

Habit:

Massive - Uniformly indistinguishable crystals forming large masses.

Habit:

Platy - Sheet forms (e.g. micas).

Hardness:

2.5-3 - Finger Nail-Calcite

Luminescence:

Non-fluorescent.

Luster:

Vitreous - Pearly

Streak:

white

Optical Properties of Lepidolite

Gladstone-Dale:

CI meas= 0.084 (Poor) - where the CI = (1-KPDmeas/KC)
CI calc= 0.064 (Fair) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1998,KPDmeas= 0.1956,KC= 0.2135
Ncalc = 1.6 - 1.62

Optical Data:

Biaxial (-), a=1.525-1.548, b=1.551-1.58, g=1.554-1.586, bire=0.0290-0.0380, 2V(Calc)=36-46, 2V(Meas)=25-58. Dispersion weak, r > v.

Pleochroism (x):

colorless.

Pleochroism (y):

colorless.

Calculated Properties of Lepidolite

Electron Density:

Bulk Density (Electron Density)=2.76 gm/cc
note: Specific Gravity of Lepidolite =2.79 gm/cc.

Fermion Index:

Fermion Index = 0.01
Boson Index = 0.99

Photoelectric:

PE_Lepidolite= 2.38 barns/electron
U=PE_Lepidolite x r_electron= 6.56 barns/cc.

Radioactivity:

GRapi = 143.68 (Gamma Ray American Petroleum Institute Units)
Concentration of Lepidolite per GRapi unit = 0.70 (%)

Estimated Radioactivity from Lepidolite - barely detectable

Lepidolite Classification

Dana Class:

71.02.02b.07 (71)Phyllosilicate Sheets of Six-Membered Rings

(71.02)with 2:1 Layers

(71.02.02b)Mica Group (Biotite subgroup)

71.02.02b.01 Phlogopite KMg3(Si3Al)O10(F,OH)2 C 2/m 2/m

71.02.02b.01a Tetraferriphlogopite! KMg3FeSi3O10(OH)2 2/m

71.02.02b.01b Shirozulite! KMn3(AlSi3)O10(OH,F)2 C 2/m 2/m

71.02.02b.01c Fluorophlogopite! KMg3(AlSi3)O10F2 C 2/m 2/m

71.02.02b.02 Biotite* K(Mg,Fe)3[AlSi3O10(OH,F)2 C 2/m 2/m

71.02.02b.03 Annite KFe3AlSi3O10(OH,F)2 C 2/m 2/m

71.02.02b.03a Fluorannite! KFe3AlSi3O10F2 C 2/m 2/m

71.02.02b.04 Tetraferriannite K(Fe,Mg)3(Fe,Al)Si3O10(OH)2 C 2/m 2/m

71.02.02b.05 Siderophyllite KFe2Al(Al2Si2)O10(F,OH)2 C 2/m 2/m

71.02.02b.05a Eastonite! KMg2Al[Al2Si2O10](OH)2 2/m

71.02.02b.06 Hendricksite K(Zn,Mg,Mn)3Si3AlO10(OH)2 C 2/m 2/m

71.02.02b.07 Lepidolite K(Li,Al)3(Si,Al)4O10(F,OH)2 C 2/m,Cm Mono

71.02.02b.08 Polylithionite KLi2AlSi4O10(F,OH)2 C 2/m 2/m

71.02.02b.08a Trilithionite! KLi1.5Al1.5AlSi3O10F2 C 2/m 2/m

71.02.02b.08b Sokolovaite! CsLi2AlSi4O10F2 C 2/m, C 2 or Cm Mono

71.02.02b.09 Tainiolite KLiMg2Si4O10F2 C 2/m 2/m

71.02.02b.10 Zinnwaldite KLiFeAl(AlSi3)O10(F,OH)2 C 2/m 2/m

71.02.02b.11 Norrishite K(Mn2Li)Si4O10(O)2 C 2/m 2/m

71.02.02b.12 Masutomilite K(Li,Al,Mn)3[(Si,Al)4O10](F,OH)2 C 2/m 2/m

71.02.02b.13 Aspidolite NaMg3AlSi3O10(OH)2 C 2/m 2/m

71.02.02b.14 Wonesite (Na,K).5(Mg,Fe,Al)3(Si,Al)4O10(OH,F)2 C 2/m 2/m

71.02.02b.15 Preiswerkite NaMg2Al3Si2O10(OH)2 C 2/m 2/m

71.02.02b.16 Ephesite NaLiAl2(Al2Si2)O10(OH)2 C 2/c 2/m

71.02.02b.18 Suhailite! (NH4)Fe3(Si3Al)O10(OH)2 C 2/m? 2/m

Strunz Class:

09.EC.20 09 - SILICATES (Germanates)

09.E - Phyllosilicates

09.EC -Phyllosilicates with mica sheets, composed of tetrahedral and octahedral nets

09.EC.20 Annite KFe3AlSi3O10(OH,F)2 C 2/m 2/m

09.EC.20 Biotite* K(Mg,Fe)3[AlSi3O10(OH,F)2 C 2/m 2/m

09.EC.20 Hendricksite K(Zn,Mg,Mn)3Si3AlO10(OH)2 C 2/m 2/m

09.EC.20 Ephesite NaLiAl2(Al2Si2)O10(OH)2 C 2/c 2/m

09.EC.20 Aspidolite NaMg3AlSi3O10(OH)2 C 2/m 2/m

09.EC.20 Lepidolite K(Li,Al)3(Si,Al)4O10(F,OH)2 C 2/m,Cm Mono

09.EC.20 Preiswerkite NaMg2Al3Si2O10(OH)2 C 2/m 2/m

09.EC.20 Masutomilite K(Li,Al,Mn)3[(Si,Al)4O10](F,OH)2 C 2/m 2/m

09.EC.20 Wonesite (Na,K).5(Mg,Fe,Al)3(Si,Al)4O10(OH,F)2 C 2/m 2/m

09.EC.20 Polylithionite KLi2AlSi4O10(F,OH)2 C 2/m 2/m

09.EC.20 Phlogopite KMg3(Si3Al)O10(F,OH)2 C 2/m 2/m

09.EC.20 Norrishite K(Mn2Li)Si4O10(O)2 C 2/m 2/m

09.EC.20 Siderophyllite KFe2Al(Al2Si2)O10(F,OH)2 C 2/m 2/m

09.EC.20 Fluorannite! KFe3AlSi3O10F2 C 2/m 2/m

09.EC.20 Shirokshinite! K(NaMg2)Si4O10F2 C 2/m 2/m

09.EC.20 Zinnwaldite KLiFeAl(AlSi3)O10(F,OH)2 C 2/m 2/m

09.EC.20 Eastonite! KMg2Al[Al2Si2O10](OH)2 2/m

09.EC.20 Tetraferriannite K(Fe,Mg)3(Fe,Al)Si3O10(OH)2 C 2/m 2/m

09.EC.20 Tetraferriphlogopite! KMg3FeSi3O10(OH)2 2/m

09.EC.20 Trilithionite! KLi1.5Al1.5AlSi3O10F2 C 2/m 2/m

09.EC.20 Sokolovaite! CsLi2AlSi4O10F2 C 2/m, C 2 or Cm Mono

09.EC.20 Shirozulite! KMn3(AlSi3)O10(OH,F)2 C 2/m 2/m

09.EC.20 Suhailite! (NH4)Fe3(Si3Al)O10(OH)2 C 2/m? 2/m

09.EC.20 Fluorophlogopite! KMg3(AlSi3)O10F2 C 2/m 2/m

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Lepidolite

K(Li,Al)3(Si,Al)4O10(F,OH)2
Dana No: 71.02.02b.07 Strunz No: 09.EC.20
Locality:

Notes: