Mineral phase
- IMA name
- Chromite
- Class
- non-silicate mineral
- Compound type
- oxide-hydroxide
- Comments
- Equivalent Space Group: Fd3m (227)
- Formula
- $Fe^{2+}\!Cr_2O_4$
- Chemical formula
- (Fe2+)Cr2O4
- Elemental formula
- (Fe2+) Cr2 O4
- Isotope mixture type
- terrestrial abundance
- Composition comments
- common impurities: considerable amount of Mg replacing $Fe^{2+}$ and Al, $Fe^{3+}$ replacing Cr, other impurities: Zn, Mn, Ti, V
- Oxides
-
Formula $Cr_{2}O_{3}$ $FeO$ Mass fraction (%) 67.9 32.1
Strunz
- Class
- oxides - hydroxides - arsenites (04)
- Division
- metal:oxygen = 3:4 and similar (04.B)
- Family
- with only medium-sized cations (04.BB)
- Code
- 04.BB.05
Dana
- Major class
- oxides and hydroxides (III)
- Class
- multiple oxides (07)
- Type
- (A+B++)2X4 Spinel group (07.02)
- Group
- Chromium subgroup (07.02.03)
- Code
- 07.02.03.03
- Phase type
- crystalline
- Crystal system
- isometric (cubic)
- Crystal class
- hexoctahedral
- Crystal class symbol
- m-3m (Oh)
- Crystal spacegroup
- Fd-3m
- Molar mass
- 223.84 $g/mol$
- Density
- 4.5-5.09 $g/cm^3$
- State NTP
- solid
- Refringence type
- isotropic
- Refringence sign
- no
- Birefringence
- 0
- Refraction index $n_{\alpha}$
- 2.08 - 2.16
- Pure color
- black
- Color
- black, brownish black
- Diaphaneity
- opaque
- Luster
- metallic