[OLD] Reacting Granite

[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.