Mineral phase
IMA name
Beidellite
Type
Class
silicate mineral
Compound type
phyllosilicate
Comments
Beidelite has a typical hydration number of 1
Chemical composition
Formula
$(Na,Ca_{0.5})_{0.3}Al_2.(Si,Al)_4O_{10}(OH)_2 \bullet n(H_2O)$
Chemical formula
(Na,Ca0.5)0.3Al2(Si,Al)4O10(OH)2•n(H2O)
Elemental formula
(Na)0-0.3 (Ca)0-0.15 (Al)2-2.5 (Si)3.5-4 O12 H2
Isotope mixture type
terrestrial abundance
  Formula Name Family Number min-max Isotope mole fraction State Relevance
$Na$ Sodium element 0 - 0.3 constituent element main
$Ca$ Calcium element 0 - 0.15 constituent element main
$Al$ Aluminium element 2 - 2.5 constituent element main
$Si$ Silicon element 3.5 - 4 constituent element main
$O$ Oxygen element 12 constituent element main
$H$ Hydrogen element 2 constituent element main
Composition comments
Typical formula: $Na_{0.5}Al_2.(Si_{3.5}Al_{0.5})O_{10}(OH)_2 \bullet (H_2O)$ - Common impurities: Ti, K, Mg, Fe
Chemical functions
  Function Number
$(OH)^-$ 2
Chemical bonds
  Bond Number
$O^--H$ 1
Oxides
Formula $Na_{2}O$ $CaO$ $Al_{2}O_{3}$ $SiO_{2}$ $H_{2}O$
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.40

Dana

Major class
silicates (VIII)
Class
phyllosilicate sheets of six-membered rings (71)
Type
with 2:1 clays (71.03)
Group
Smectite group (Dioctahedral Smectites) (71.03.01a)
Code
71.03.01a.01
Phase type
crystalline
Crystal system
monoclinic
Crystal class
prismatic
Crystal class symbol
2/m (C2h)
Crystal spacegroup
C2/m
Molar mass
389.27 $g/mol$
Density
2-2.3 $g/cm^3$
State NTP
solid
Refringence type
biaxial
Refringence sign
negative
Birefringence
0.030 - 0.032
Refraction index $n_{\alpha}$
1.494 - 1.503
Refraction index $n_{\beta}$
1.525 - 1.532
Refraction index $n_{\gamma}$
1.526 - 1.533
Dispersion V
0
Pure color
white
Color
white, gray, reddish white, brownish white, pale yellow
Diaphaneity
translucent to subtranslucent
Luster
earthy
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