Talc

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]


ItokasiÀtúnṣe

  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