Concentration of condensed species in a model with T_eff = 1300 K, log g =3, and β′ = 1, showing a secondary cloud layer almost entirely made of di-sodium sulfide Na₂ S[s]. is the number density of solid units of condensed species s, is the volume occupied by one unit of solid s in the pure material, and m_s is the mass of one such unit, for example 100.4 amu for s = MgSiO₃. is directly comparable to element abundances.