Home > Data consultation > Mineral species
 
Mineral speciesFormula
 EskolaiteCr2O3 
Mineralogy
Space group: Trigonal - Hexagonal Scalenohedral HM symbol (-3 2/m) Space Group: R 3c 
Dana class: 4.3.1.3III - 4 Oxide Minerals ; 4.3 Simple Oxides with a cation charge of 3+ (A+++2 O3) ; 4.3.1 Corundum-Hematite group (Rhombohedral: R3_c) 
Geological context
Geological context: In chromium-rich tremolite skarns, metaquartzites, and chlorite veins (Outokumpu, Finland); on greywacke pebbles in a glacial boulder clay deposit (Callowhill Upper, Ireland); as pebbles in streams (Merume River, Guyana); a very rare component in chondrite meteorites. 
Thermodynamics
Individual properties
Molar weight: 151.930 g/mol  ΔGºf-1,058,862 J/mol ref.  Sº: 81.15 J/mol/K ref. 
  ΔHºf-1,140,500 J/mol ref.  Cp: 120.19 J/mol/K ref. 
Reaction properties
Chemical reaction:  Eskolaite + 6H+ = 2Cr+3 + 3H2O 
log10(Keq) = A + B.T + C.T-1 + D.log10(T) + E.T−2 (with T expressed in Kelvin)
A B C D E
 -9.88183463e+2   -1.58342559e-1   6.04015534e+4   3.52253732e+2   -2.76170093e+6 
Van t'Hoff
@ 25°C, 1 bar: log 10(Keq)7.76
ΔH°r-27,640 J/mol ref.
T (ºC) : 0 25 60 100 150 200 250 300
log 10(Keq):  10.91   7.76   4.10   0.72   -2.68   -5.50   -8.00   -10.35 
Maier Kelley
Cp(T) = a + b*10-3T + C*105T-2 (with T expressed in Kelvin)  ref.
a:49.39 J/mol/K 
b:101.34 J/mol/K2 
c:36.08 J.K/mol 

Home | Legal information | Private area | Contact us | RSS 2.0 BRGM − 3, avenue Claude Guillemin − 45060 Orléans Cedex 2