Constituent
Name
Talc
IMA name
Talc
Class
silicate mineral
Compound type
phyllosilicate
Relevance
main - major
Arrangement
single phase
Mass fraction
1.0
Formula
$Mg_3Si_4O_{10}(OH)_2$
Chemical formula
Mg3Si4O10(OH)2
Elemental formula
Mg3 Si4 O12 H2
Isotope mixture type
terrestrial abundance
  Formula Name Family Number min-max Isotope mole fraction State Relevance
$Mg$ Magnesium element 3 constituent element main
$Si$ Silicon element 4 constituent element main
$O$ Oxygen element 12 constituent element main
$H$ Hydrogen element 2 constituent element main
Chemical functions
  Function Number
$(OH)^-$ 2
Chemical bonds
  Bond Number
$O^--H$ 1
Oxides
Formula $MgO$ $SiO_{2}$ $H_{2}O$
Mass fraction (%) 31.88 63.37 4.75

Strunz

Class
silicates (09)
Division
phyllosilicate (09.E)
Family
Phyllosilicates with mica sheets, composed of tetrahedral and octahedral nets (09.EC)
Code
09.EC.05

Dana

Major class
silicates (VIII)
Class
phyllosilicate sheets of six-membered rings (71)
Type
with 2:1 layers (71.02)
Group
Pyrophyllite-talc group (71.02.01)
Code
71.02.01.03
Phase type
crystalline
Crystal system
monoclinic
Crystal class
prismatic
Crystal class symbol
2/m (C2h)
Crystal spacegroup
C2/c
Texture
monocrystalline
Molar mass
379.27 $g/mol$
Density
2.7 - 2.8 $g/cm^3$
Refringence type
biaxial
Refringence sign
negative
Birefringence
0.037 - 0.05
Refraction index $n_{\alpha}$
1.538 - 1.55
Refraction index $n_{\beta}$
1.575 - 1.594
Refraction index $n_{\gamma}$
1.575 - 1.6
Color
pale green, white, gray white, yellowish white, brownish white
Diaphaneity
translucent
Luster
vitreous