Mineral phase
IMA name
Nepouite
Secondary names
Genthite
Type
Class
silicate mineral
Compound type
phyllosilicate
Chemical composition
Formula
$Ni_3.Si_2O_5(OH)_4$
Chemical formula
Ni3Si2O5(OH)4
Elemental formula
Ni3 Si2 O9 H4
Isotope mixture type
terrestrial abundance
  Formula Name Family Number min-max Isotope mole fraction State Relevance
$Ni$ Nickel element 3 constituent element main
$Si$ Silicon element 2 constituent element main
$O$ Oxygen element 9 constituent element main
$H$ Hydrogen element 4 constituent element main
Composition comments
Common substitution of Ni: Mg (sometimes in the formula: $(Ni,Mg)_3.Si_2O_5(OH)_4$) - Common impurities: Al, Fe, Ca, Na, K
Chemical functions
  Function Number
$(OH)^-$ 4
Chemical bonds
  Bond Number
$O^--H$ 1
Oxides
Formula $NiO$ $SiO_{2}$ $H_{2}O$
Mass fraction (%) 58.92 31.6 9.48

Strunz

Class
silicates (09)
Division
phyllosilicate (09.E)
Family
Phyllosilicates with kaolinite layers (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.03
Phase type
crystalline
Crystal system
orthorhombic
Crystal class
pyramidal
Crystal class symbol
mm2 (C2v)
Crystal spacegroup
Cmc2(1)
Molar mass
380.27 $g/mol$
Density
2.5 - 3.2 $g/cm^3$
State NTP
solid
Refringence type
biaxial
Refringence sign
negative
Birefringence
0.020 - 0.035
Refraction index $n_{\alpha}$
1.60 - 1.63
Refraction index $n_{\beta}$
1.576 - 1.579
Refraction index $n_{\gamma}$
1.635 - 1.65
Dispersion V
r > v medium
Pure color
green
Color
pale green, deep green
Diaphaneity
translucent to subtranslucent
Luster
vitreous
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