Mineral phase
IMA name
Portlandite
Secondary names
Calcium dihydroxide
CAS number
1305-62-0
Type
Class
non-silicate mineral
Compound type
oxide-hydroxide
Chemical composition
Formula
$Ca(OH)_2$
Chemical formula
Ca(OH)2
Elemental formula
Ca O H (O-)
Isotope mixture type
terrestrial abundance
  Formula Name Family Number min-max Isotope mole fraction State Relevance
$Ca$ Calcium element 1 constituent element main
$O$ Oxygen element 1 constituent element main
$(OH)^-$ Hydroxide anion chemical function 1 anionic radical main
Composition comments
Common impurities: ?
Chemical functions
  Function Number
$(OH)^-$ 2
Chemical bonds
  Bond Number
$O^--H$ 1
Oxides
Formula $CaO$ $H_{2}O$
Mass fraction (%) 975.6 24.31

Strunz

Class
oxides - hydroxides - arsenites (04)
Division
hydroxides (without V or U) (04.F)
Family
Hydroxides with OH, without H2O; sheets of edge-sharing octahedral (04.FE)
Code
04.FE.05

Dana

Major class
oxides and hydroxides (III)
Class
hydroxides and oxides containing hydroxyl (06)
Type
where X++ (OH)2 (06.02)
Group
Brucite group (Rhombohedral: P-3m1) (06.02.01)
Code
06.02.01.04
Phase type
crystalline
Crystal system
trigonal
Crystal class
ditrigonal-scalenohedral
Crystal class symbol
-3m (D3d)
Crystal spacegroup
P-3m1
Crystal sites
Label Nb Type Wp Specie Specie coordinence Specie occupancy Specie oxidation state
Ca 1 main 1a-3m.  $Ca^{2+}$ trigonal prismatic VI 1.0 2
O 2 main 6i.m.  $O$ 1.0 -1
H 6 main 6i.m.  $H$ linear I 0.333
Molar mass
74.09 $g/mol$
Density
2.227 - 2.233 $g/cm^3$
State NTP
solid
Refringence type
uniaxial
Refringence sign
negative
Birefringence
0.027
Refraction index $n_o$ (w)
1.574
Refraction index $n_e$ (e)
1.547
Pure color
colorless
Color
light yellow
Diaphaneity
transparent
Luster
pearly
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