Jump to content
Geochemist's Workbench Support Forum

What is the best method to make a phase diagram of montmorillonite-illite diagenesis?

Recommended Posts

Hi, this is Jeonghwan Hwang.

I wan't to make the phase diagram for montmorillonite-illite diagenesis using temperature and pressure.

But i cannot find the montmorillonite in any mineral information.

How to find the montmorillonite? I am very pleased to help me.


Sincerely, Jeonghwan Hwang


Link to comment
Share on other sites

Hi Jeonghwan Hwang,

There are various thermodynamic datasets installed with the software. You can search through them for minerals that you need. In a text editor, you might try to search (ctrl+F) on smectite or clay to find minerals of that type that would be representative of a montmorillonite group mineral. Or in TEdit, the GWB’s graphical thermo data editor, you can use the filter option to show only minerals with Al+++, SiO2(aq), etc to find the clays.

If you don’t see the mineral you need in any of the datasets, you can add a new mineral using information from the literature. You need to supply its reaction and log K at one or more temperatures, as well as its mole weight and mole volume.  

For more information, please see the Thermo Datasets chapter in the GWB Reference Manual and the Using TEdit chapter in the GWB Essentials Guide.


Brian Farrell
Aqueous Solutions LLC 

Link to comment
Share on other sites

Hi, Thank you for your kind help.

I can find the thermodynamic datasets which contain the imformation of montmorillonite. (thermo.com.V8.R6)

And i also find the reference script of montmorillonite-illite phase diagram which were made by GWB.

Unfortunately, i cannot make the phase diagram like capture.jpg... But i don't know what is main problem...

Can anybody tell me about my mistake? 

Thank you,


Sincerely, Jeonghwan Hwang




Link to comment
Share on other sites

Hi Jeonghwan Hwang,

I’m glad to hear that you found the minerals you need.

As stated in the figure caption, you can swap Boehmite for Al++ in the “diagram species” section, K-feldspar for K+ in the “in the presence of” section, and Calcite for Ca++ in the “in the presence of section”. To include K-felspar in the "In the presence of" section, you should first add Mg++ as the Y axis variable, then swap in K+^2/Mg++. That way you can add K+ to "in the presence of" section and swap it out for K-feldspar

After you plot a diagram, you can click View Results to the see the list of assumptions, reactions, and equilibrium lines that go into making a diagram.

Hope this helps,

Link to comment
Share on other sites

  • 2 weeks later...

Thank you for your kind help.

Now, I roughly made a phase diagram with Ca-Montmorillonite and illite.

I used 'Thermo.com.V8R6+' database.


And, I have a new question right now.

Is this phase diagram meaningful? If not, how can i make it more meaningful?

How can i know or tell the meaning of phase diagram?


I know that it is very basic question and feel sorry to ask it.

But i cannot find it at GWB guide... 


Very very thank you for your kindly help.


Sincerely, Jeonghwan Hwanga



Link to comment
Share on other sites

You’ll probably know better than anyone whether your diagram is meaningful for your study. Typically, you think about the reactions that might occur in your system, then use those reactions to build a stability diagram. To understand how Act2 constructs the diagram, you can view Act2’s output file, which reports the various assumptions made, the reactions considered, and the values of the equilibrium constants for those reactions. Or, you can use Rxn to look at each of the equilibrium lines individually.

I’ve included below two classic references on stability diagrams in geochemistry, but many textbooks will include at least some information on constructing stability diagrams.

Bowers, T.S., K.J. Jackson and H.C. Helgeson, 1984, Equilibrium Activity Diagrams. Springer-Verlag, Berlin, 397 p.

Garrels, R.M. and C.L. Christ, 1965, Solutions, Minerals, and Equilibria. Freeman, Cooper & Co., San Francisco, 450 p.

Hope this helps,

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...