Mineral phase
IMA name
Greenalite
Type
Class
silicate mineral
Compound type
phyllosilicate
Comments
Molar mass and optical properties for $Fe^{2+}_{2.3}Fe^{3+}_{0.5}Si_{2.2}O_5(OH)_{3.3}$ - Several polytypes: 1M, 2M1, 3A, 1A, 2A, 3R
Chemical composition
Formula
$(Fe^{2+}_{1-x},Fe^{3+}_{0.67x})_3.Si_2O_5(OH)_4 \ \ \ \ \ $ where $x=0-1$
Chemical formula
(Fe2+,Fe3+)2-3Si2O5(OH)4
Elemental formula
(Fe2+)2-3 (Fe3+)0-1 (Si)2-2.5 (O)8-9 (H)3-4
Isotope mixture type
terrestrial abundance
  Formula Name Family Number min-max Isotope mole fraction State Relevance
$Fe^{2+}$ Iron(II) cation element 2 - 3 constituent element main
$Fe^{3+}$ Iron(III) cation element 0 - 1 constituent element main
$Si$ Silicon element 2 - 2.5 constituent element main
$O$ Oxygen element 8 - 9 constituent element main
$H$ Hydrogen element 3 - 4 constituent element main
Composition comments
Number of Si and OH can significantly vary, typical: $Fe^{2+}_{2.3}Fe^{3+}_{0.5}Si_{2.2}O_5(OH)_{3.3}$ - Common impurities: Al, Mn, Mg
Chemical functions
  Function Number
$(OH)^-$ 4
Chemical bonds
  Bond Number
$O^--H$ 1
Oxides
Formula $FeO$ $Fe_{2}O_{3}$ $SiO_{2}$ $H_{2}O$
Mass fraction (%) 46.64 11.27 37.31 8.39
Oxides comments
for $Fe^{2+}_{2.3}Fe^{3+}_{0.5}Si_{2.2}O_5(OH)_{3.3}$

Strunz

Class
silicates (09)
Division
phyllosilicate (09.E)
Family
with kaolinite layers composed of tetrahedral and octahedral nets (09.ED)
Code
09.ED.15

Dana

Major class
silicates (VIII)
Class
phyllosilicate sheets of six-membered rings (71)
Type
with 1:1 layers (71.01)
Group
Serpentine group (Lizardite subgroup) (71.01.02b)
Code
71.01.02b.04
Phase type
crystalline
Crystal system
monoclinic
Crystal class
unknown
Crystal class symbol
unknown
Crystal spacegroup
unknown
Molar mass
354.28 $g/mol$
Density
2.85 - 3.15 $g/cm^3$
State NTP
solid
Refringence type
biaxial
Refringence sign
positive
Birefringence
0.001 - 0.024
Refraction index $n_{\alpha}$
1.65 - 1.675
Refraction index $n_{\beta}$
1.674
Refraction index $n_{\gamma}$
1.674
Dispersion V
weak
Pure color
green
Color
blue green, light yellow green, dark green, black
Diaphaneity
translucent to opaque
Luster
earthy
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