Mineral phase
IMA name
Eskolaite
IMA Code
Esk
CAS number
1308-38-9
Class
non-silicate mineral
Compound type
oxide
Formula
$Cr_2O_3$
Chemical formula
Cr2O3
Elemental formula
Cr2 O3
Isotope mixture type
terrestrial abundance
  Formula Name Family Number min-max Isotope mole fraction State Relevance
$Cr$ Chromium element 2 constituent element main
$O$ Oxygen element 3 constituent element main
Chemical bonds
  Bond Number
$>Cr-O$ 6
Oxides
Formula $Cr_{2}O_{3}$
Mass fraction (%) 100.0

Strunz

Class
oxides - hydroxides - arsenites (04)
Division
metal:oxygen = 2:3, 3:5, and similar (04.C)
Family
with medium-sized cations (04.CB)
Code
04.CB.05

Dana

Major class
oxides and hydroxides (III)
Class
simple oxides (04)
Type
with a cation charge of 3+ (A+++2O3) (04.03)
Group
Corundum-Hematite group (Rhombohedral: R-3c) (04.03.01)
Code
04.03.01.03
Phase type
crystalline
Crystal system
trigonal
Crystal class
ditrigonal-scalenohedral
Crystal class symbol
-3m (D3d)
Crystal spacegroup
R-3c
Molar mass
151.99 $g/mol$
Density
5.18 $g/cm^3$
State NTP
solid
Refringence type
uniaxial
Refringence sign
unknown
Pure color
green
Color
black, dark green
Diaphaneity
translucent to opaque
Luster
vitreous