Mineral phase
IMA name
Grimaldiite
IMA Code
Gmd
Type
Class
non-silicate mineral
Compound type
oxide-hydroxide
Chemical composition
Formula
$CrO(OH)$
Chemical formula
CrO(OH)
Elemental formula
Cr O2 H
Isotope mixture type
terrestrial abundance
  Formula Name Family Number min-max Isotope mole fraction State Relevance
$Cr$ Chromium element 1 constituent element main
$O$ Oxygen element 2 constituent element main
$H$ Hydrogen element 1 constituent element main
Chemical bonds
  Bond Number
$>Cr-O$ 2
$-O-H$ 1
$-O \dots H-$ 1
Oxides
Formula $Cr_{2}O_{3}$ $H_{2}O$
Mass fraction (%) 89.4 10.6

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.20

Dana

Major class
oxides and hydroxides (III)
Class
hydroxides and oxides containing hydroxyl (06)
Type
where X+++O OH (06.01)
Group
-Grimaldiite- group (06.01.05)
Code
06.01.05.01
Phase type
crystalline
Crystal system
trigonal
Crystal class
ditrigonal-scalenohedral
Crystal class symbol
-3m (D3d)
Crystal spacegroup
R-3m
Molar mass
85.00 $g/mol$
Density
4.11 $g/cm^3$
State NTP
solid
Refringence type
uniaxial
Refringence sign
negative
Birefringence
0.18
Refraction index $n_o$ (w)
2.155
Refraction index $n_e$ (e)
1.975
Pure color
red
Color
dark red, reddish brown
Diaphaneity
opaque
Luster
metallic
Links