Lepidolite

Lepidolite
General
CategoryPhyllosilicate
Formula
(repeating unit)
K(Li,Al)3(Al,Si,Rb)4O10(F,OH)2
IMA symbolLpd[1]
Strunz classification9.EC.20
Crystal systemMonoclinic
Crystal classPrismatic (2/m)
(same H-M symbol)
Space groupC2/m, Cm
Unit cella = 5.209(2) Å, b = 9.011(5) Å,
c = 10.149(5) Å;
β = 100:77(4)°; Z = 2
Identification
ColorPink, light purple, purple, rose-red, violet-gray, yellowish, white, colorless other colors possible but are rare.
Crystal habitTabular to prismatic pseudohexagonal crystals, scaly aggregates and massive
TwinningRare, composition plane {001}
Cleavage{001} perfect
FractureUneven
Mohs scale hardness2.5–3
LusterVitreous to pearly
StreakWhite
DiaphaneityTransparent to translucent
Specific gravity2.8–2.9
Optical propertiesBiaxial (−)
Refractive indexnα=1.525–1.548, nβ=1.551–1.58, nγ=1.554–1.586
Birefringence0.0290–0.0380
PleochroismX = almost colorless; Y = Z = pink, pale violet
2V angle0° – 58° measured
References[2][3]

Lepidolite is a lilac-gray or rose-colored member of the mica group of minerals with chemical formula K(Li,Al)3(Al,Si,Rb)4O10(F,OH)2.[2][3] It is the most abundant lithium-bearing mineral[4] and is a secondary source of this metal. It is the major source of the alkali metal rubidium.

Lepidolite is found with other lithium-bearing minerals, such as spodumene, in pegmatite bodies. It has also been found in high-temperature quartz veins, greisens and granite.

  1. ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. ^ a b Anthony, John W.; Bideaux, Richard A.; Bladh, Kenneth W.; Nichols, Monte C. (2005). "Lepidolite" (PDF). Handbook of Mineralogy. Mineral Data Publishing. Retrieved 14 March 2022.
  3. ^ a b Barthelmy, David (2014). "Lepidolite Mineral Data". Webmineral.com. Retrieved 19 March 2022.
  4. ^ Deer, W.A.; Howie, R.A.; Zussman, J. (1966). An Introduction to the Rock Forming Minerals. London: Longman. p. 218. ISBN 0-582-44210-9.

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