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Talc

Lát'ọwọ́ Wikipedia, ìwé ìmọ̀ ọ̀fẹ́
Talc
Crystals of talc.
General
CategorySilicate mineral
Chemical formulaMg3Si4O10(OH)2
Identification
Colorwhite, grey, green, blue, or silver
Crystal habitfoliated to fibrous masses
Crystal systemMonoclinic or Triclinic[1]
Cleavageperfect basal cleavage
FractureFlat surfaces (not cleavage) fracture in an uneven pattern
TenacitySectile
Mohs scale hardness1
Lusterwaxlike or pearly sometimes smooth
StreakWhite
DiaphaneityTranslucent
Specific gravity2.58 to 2.83
Optical propertiesBiaxial (-)
Refractive indexnα = 1.538 - 1.550 nβ = 1.589 - 1.594 nγ = 1.589 - 1.600
Birefringenceδ = 0.051
PleochroismWeak in dark varieties
Other characteristicsFluorescent
References[2][3][4]

Talc



  1. An Introduction to the Rock-Forming Minerals, second edition, by W.A. Deer, R.A. Howie, and J. Zussman, 1992, Prentice Hall, ISBN 0-582-30094-0.
  2. http://rruff.geo.arizona.edu/doclib/hom/talc.pdf Handbook of Mineralogy
  3. http://www.mindat.org/min-3875.html Mindat.org
  4. http://webmineral.com/data/Talc.shtml Webmineral data