Dissolution reaction kinetics for Birnessite

[sabber]

Dear all,

I want to simulate kinetic batch reaction of dissolution for a mixture of minerals using PHREEQC. One of these minerals is Birnessite. I searched the literature, but I could not find the TST coefficients for this mineral. Is it OK if I replace it by another (Mn, O) mineral? What is the common policy to address it?

Thank you in advance for your help.