Mineral phase
IMA name
Saponite-Hectorite-Sauconite series
Secondary names
Trioctahedral Smectites series
Type
Class
silicate mineral
Compound type
phyllosilicate
Chemical composition
Formula
$(Ca_{0.5},Na_{0.3})(Mg,Li,Fe,Al)_3.(Si,Al)_4O_{10}(OH)_2 \bullet n(H_2O)$
Chemical formula
[Na(1-x)Ca0.5(1+x)]0.3[(Mg)x(Fe2+)y(Li)z(Zn)1-x-y-z]3[(Si)x(Al)1-x]4O10(OH)2•n(H2O)
Elemental formula
(Na)0-0.5 (Ca)0-0.15 (Mg)0-3 (Fe2+)0-1 (Li)0-0.5 (Zn)0-3 (Al)0-1.5 (Si)2.5-4 O12 H2
Isotope mixture type
terrestrial abundance
  Formula Name Family Number min-max Isotope mole fraction State Relevance
$Na$ Sodium element 0 - 0.5 constituent element main
$Ca$ Calcium element 0 - 0.15 constituent element main
$Mg$ Magnesium element 0 - 3 constituent element main
$Fe^{2+}$ Iron(II) cation element 0 - 1 constituent element main
$Li$ Lithium element 0 - 0.5 constituent element main
$Zn$ Zinc element 0 - 3 constituent element main
$Al$ Aluminium element 0 - 1.5 constituent element main
$Si$ Silicon element 2.5 - 4 constituent element main
$O$ Oxygen element 12 constituent element main
$H$ Hydrogen element 2 constituent element main
Composition comments
Partial solid solution - Common impurities: Ti, Mn, Cu, Ni, K, P, Cl
Chemical functions
  Function Number
$(OH)^-$ 2
Chemical bonds
  Bond Number
$O^--H$ 1
Oxides
Formula $Na_{2}O$ $CaO$ $MgO$ $FeO$ $Li_{2}O$ $ZnO$ $Al_{2}O_{3}$ $SiO_{2}$ $H_{2}O$
Mass fraction (%)

Strunz

Class
silicates (09)
Division
phyllosilicate (09.E)
Family
with mica sheets, composed of tetrahedral and octahedral nets (09.EC)
Code
09.EC.45

Dana

Major class
silicates (VIII)
Class
phyllosilicate sheets of six-membered rings (71)
Type
with 2:1 clays (71.03)
Group
Smectite group (Trioctahedral Smectites) (71.03.01b)
End-members
Phase type
crystalline
Crystal system
monoclinic
Crystal class
prismatic
Crystal class symbol
2/m (C2h)
Crystal spacegroup
C2/m
Molar mass
383.25 - 580.37 $g/mol$
Density
2.0 - 3.0 $g/cm^3$
State NTP
solid
Refringence type
biaxial
Refringence sign
negative
Birefringence
0.030 - 0.040
Refraction index $n_{\alpha}$
1.479 - 1.58
Refraction index $n_{\beta}$
1.50 - 1.62
Refraction index $n_{\gamma}$
1.511 - 1.62
Pure color
white
Diaphaneity
translucent to opaque
Luster
earthy
Links