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Mineral speciesFormula
 Cinnabar(beta)HgS 
Mineralogy
Family: Cinnabarite - Hypercinnabarite series 
Space group: Trigonal - Trapezohedral H-M Symbol (3 2) Space Group: P 3121,P 3221 
Dana class: 2.8.14.1 (2)Sulfides - Including Selenides and Tellurides (2.8)where Am Bn Xp, with (m+n):p=1:1 (2.8.14) Dana Group 
Geological context
High temperature: At 25C cinnabar is a metastable mineral, a gentle desulphuration can release drops of mercury. 
Geological context: Low temperature hydrothermal solutions in veins. Oxidized mercury deposits, supergene environment. 
Thermodynamics
Individual properties
Molar weight: 232.656 g/mol  ΔGºf-43,534 J/mol ref.   
   Cp: 46.37 J/mol/K ref. 
Reaction properties
Chemical reaction:  Cinnabar(beta) + H+ = HS- + Hg+2 
log10(Keq) = A + B.T + C.T-1 + D.log10(T) + E.T−2 (with T expressed in Kelvin)
A B C D E
 -9.13129824e+2   -1.45545126e-1   3.87233709e+4   3.31550653e+2   -2.87795553e+6 
Van t'Hoff
@ 25°C, 1 bar: log 10(Keq)-38.62
T (ºC) : 0 25 60 100 150 200 250 300
log 10(Keq):  -41.90   -38.62   -34.92   -31.61   -28.46   -26.11   -24.39   -23.24 
Maier Kelley
Cp(T) = a + b*10-3T + C*105T-2 (with T expressed in Kelvin)  ref.
a:49.21 J/mol/K 
b:11.95 J/mol/K2 
c:-5.69 J.K/mol 

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