What is Petrolog?

Q. Are there limitation to the compositions of magma that can be modelled with Petrolog4?

A. Yes, the range of magma compositions and crystallisation conditions that can be modelled by Petrolog4 is limited by the availability of published phase – silicate melt equilibrium models. Petrolog4 (v.4.0.6) does not include any models for amphibole, mica, alkali feldspar, quartz and apatite. This does not allow for modelling of anhydrous diorite – rhyolite compositions and hydrous andesites – diorite – rhyolite compositions.

Q. Is Petrolog4 different from other modelling software?

A. Yes, Petrlog4 uses a different conceptual approach to crystallisation modelling and a different algorithm, and it also offers a range of additional tools that are not available in other modelling software. You can read more about Petrolog4's approach to modelling here.

Installation and licencing

Q. How much will Petrolog4 licence cost?

A. Please see the Pricing section of this website

Q. Will the full version of Petrolog4 be free?

A. No, using Petrolog4 will require purchasing an annual licence.

Q. Are there any benefits for those users who purchase a licence for Petrolog4?

A. Yes, In addition to having access to all features of the software, Petrolog4 licence holders receive priority support and can submit requests for adding new models and features to Petrolog4.

Q. Petrolog4 does not remember the licence information and keeps requesting licence information while I run the program. Is this the expected behaviour?

A. No, Petrolog4 checks for licence once every time the program is started, and it would not request the licence information after the first time it was entered if the same user is logged on to the computer that runs Petrolog4.
The above behaviour may be observed if Petrolog4 is placed in a shared/managed folder, i.e., a folder that is administered by OneDrive, Dropbox, Google Drive, or other file sharing software.
We suggest making a folder C:\Petrolog4 or C:\Programs\Petrolog4 and running PEtrolog4 from that folder.

Previous versions of Petrolog

Q. Will Petrolog3 continue to be available for free?

A. Yes, Petrolog3 can be downloaded for free from here

Petrolog on Mac

Q. Will Petrolog4 be available on macOS?

A. Mac users can run the current version of Petrolog4 on their computer after installing Windows under a virtual machine (e.g., www.parallels.com). Releasing a macOS version of Petrolog4 is planned for the future, however its release will be dependent on the number of licensed users.

Petrolog developers

Q. Are Leonid and Pavel still involved with Petrolog development and maintenance?

A. Yes, both Leonid and Pavel are continue to be the main developers of Petrolog.

Using Petrolog

Q. Are there recommended sets of calculation parameters for different magma types?

A. Yes, available files with recommended parameter settings are included with Petrolog when it is downloaded from this website. The files can also be downloaded here.

Q. Can I discuss the choice of calculation parameters for my projects with the developers?

A. Yes, Petrolog licence holders can email questions to support@petrologsoftware.com. We aim to respond as soon as possible within 5 business days.

Q. Can Petrolog start with my preferred set of parameters?

A. Yes, save your preferred set of parameters as the Default parameter set (use 'Save parameters as the Default set' option under the File menu). After that, Petrolog will load this set of parameters every time you start the software.

Q. Can I stop loading the Default set of parameters when I start Petrolog?

A. Yes, you can delete (or rename) Default.PtlParam file from the folder where you keep Petrolog executable file.

Q. Does it matter which model for the oxidation state of Fe in the melt is chosen for calculation?

A. Yes, this affects the compositions of Fe-Mg minerals and calculated pseudo-liquidus temperatures and compositions of some oxide minerals. For more details see ‘Does it matter which model for the extent of Fe oxidation in silicate melt is chosen for calculations?’ presentation and ‘Defining melt oxidation state during calculations’ tutorial.

Q. Does it matter which model for the sulphide for sulphide saturation of silicate melt is chosen for calculation?

A. Yes, this may have a significant impact on the inferred timing of sulphide saturation, the calculated amount of immiscible sulphide, and the predicted trends of S, Ni and Cu contents during crystallisation. For more details see ‘Does it matter which model for sulphide saturation of silicate melt is chosen for calculations?’ presentation.

Melt Inclusion modelling

Q. Are there changes to the Melt Inclusion modelling in Petrolog4 compared to Petrolog3?


Yes, the diffusion coefficient for Fe-Mg inter-diffusion in olivine is calculated as a function of temperature and olivine composition in Petrolog4, derived using a linear regression of experimental data from from Chakraborty (1997). The equation is presented in the Manual.

Petrolog4 allows for modelling diffusive re-equilibration with a specific cooling rate over a cooling interval of up to 400 oC, whereas in Petrlog3 the cooling interval is limited to 100 oC.