[rockwebmaster]

From: Sadoon Morad
Subject: reacting granite
As a beginner with poor knowledge in using GWB, I need help in performing, among many other things, the followings tasks:
1. perform the flow-through modelling of, for example, the reaction of 10 kg granitic rock composed of 4 kg oligoclase, 2 kg quartz, 2 kg microcline, and 2 kg Fe-Mg biotite with 1 kg meteoric water.
2. how to decide which phases to be incorporated in an equilibrium diagram such as in Figure 3.3 in the Users' Guide. For example, how can I include clinozoisite into the diagram?

From: Craig Bethke
Subject: Re: reacting granite
This procedure should work:
1) Equilibrate the flushing fluid
2) Pick this fluid up as a reactant
3) Use “reactants times� to set the desired mass
4) Set up the main system to include the desired minerals and initial fluid
5) Set the “flush� option
6) Type “go�
You might want to use smaller masses for the minerals, however, since it will take quite a long time to reactant such large amounts. To include include clinozoisite into the diagram - You need to set the Ca++/H+^2 ratio, or use it as an axis, in order to bring clinozoisite into consideration. Example:
T = 300 C
swap Kaolinite for Al+++
swap Quartz for SiO2(aq)
swap Ca++/H+^2 for Ca++
swap Na+/H+ for Na+
diagram Kaolinite on Na+/H+ vs Ca++/H+^2
x 0 15
y 0 10
suppress Prehnite Grossular
Note the clinozoisite doesn't appear as a stable phase in this diagram unless prehnite and grossular are suppressed.