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Introduction to phase diagrams

File structures, file names and line endings


Calculating phase diagrams


av PT Calculations

activity-composition model documentation

Mineral abbreviations

Input file documentation

Output file documentation

Internally consistent dataset documentation



page last updated: 28.11.2011


This section contains the basic documentation for using thermocalc. This page is still incomplete. The contents of documentation pages are outlined below.

Thermocalc Course Documentation

2006 Sao Paulo, Brazil

The course documents and lecture material of 2006 Sao Paulo, Brazil thermocalc short course can be downloaded below (please note some of this material is now out of date).  This download is the same material as the course CD and contains the basic documentation and lecture material from Roger Powell and Richard White, Contents of this course are copyright Roger Powell & Tim Holland. If you wish to reference any of the course material the reference is:

Roger Powell and Tim Holland, 2006. Course Notes for "THERMOCALC Short Course"  (Sao Paulo, Brazil) on CD-ROM.

Download Sao Paulo short course notes (6MB zip file)


2009 Prague, Czech Republic

Some newer course material from the 2009 Prague short course is available from the 2009 Prague Short Course Page.


Book - Equilibrium Thermodynamics in Petrology

Roger Powell’s 1978 book “Equilibrium Thermodynamics in Petrology” is now available as a PDF file. The book is made available with the permission of the copyright holder, Roger Powell. The book is for personal, non commercial use only. Please note this file is 14Mb.

Download Powell 1978, Equilibrium Thermodynamics in Petrology


Introduction to phase diagrams

The information in this page is a short outline of the key aspects of metamorphic phase diagrams written by Roger Powell. If you are new to metamorphic phase diagrams these notes should help you understand the basics and the terminology used. 

Detailed information can be found on the introduction to phase diagrams page.


Calculating phase diagrams

This section outlines the basic instructions for calculating phase diagrams using thermocalc, It is in part based on the course CD notes and the information in:

Powell, R, Holland, TJB, & Worley, B, 1998. Calculating phase diagrams involving solid solutions via non-linear equations, with examples using THERMOCALC Journal of Metamorphic Geology 16, 577–588.

Detailed information can be found on the calculating phase diagrams page.


File structures, file names and line endings

Thermocalc reads information from a number of files which contain information  (e.g. the dataset, a-x relations, scripts). During a run it also produces or overwrites a number of files. Over the years, the naming structure for these files has changed as has the form of some of the code within them.  One of the more recent changes (version 3.30 and later) has been the separation of the datafile scripting from the a-x relationships.

Detailed information can be found on the file structure page.


Thermocalc scripts

The information on this page pertains to using scripts in thermocalc (for scripts in drawpd, see the drawpd documentation). This list is an updated version of the list given in the course CD documentation originally compiled by Roger Powell and updated now by Richard White.

Detailed information can be found on the scripts page.


Drawpd documentation

Drawpd is a program for converting thermocalc output (from the tc-name-dr file) into a diagram. Lines, points and field information is collected in a drawpd text input file with a name structure of  “dr d<name>.txt” along with a number of scripts that define the x & y axes, the x & y values for the window, labelling of axes and the colour of the area fills, amongst other things. Drawpd then converts this information into a postscript (.ps) file.

Detailed information can be found on the drawpd documentation page.


Average PT calculations documentation

Updated: 16/05/2010

Average PT calculations are the standard thermocalc thermobarometry calculations (ie calcmode 3). In calcmode 3, thermocalc reads a simple file of endmembers, their activities and the uncertainties on their activities derived from electron probe micro analysis and performs a thermobarometric calculation on an independent set of reactions written between these endmembers.

Detailed information can be found on the average PT documentation


Activity-composition models for phase diagrams

Each mineral that exhibits solid-solution in a given chemical system must have an activity-composition (a-x) model that describes the distribution of elements on sites and the interaction energies. This page outlines the different kinds of models available and how they are coded in the ax files.

Detailed information can be found on the activity composition models page.


List of Mineral and Phase Abbreviations

The Mineral and Phase Abbreviations page provides a list of commonly used abbreviations for mineral and phase names used in thermocalc.


Thermocalc input

This page explains the information that is in the main thermocalc input files for phase diagram calculations. The input files are

The internally consistent dataset – eg tc-ds55
The global preferences file – tc-prefs
The script file – eg tc-ptpseudo
The activity-composition file – eg tc-NCKFMASHp

Detailed information can be found on the thermocalc input documentation page.


Thermocalc output

Three output files are produced each time thermocalc is run and each of these files contains different information and is in different formats. The three output files are:


Detailed information can be found on the thermocalc output documentation page.


Internally consistent dataset documentation

This section outlines the differences and changes between the different generations of the dataset.

More information can be found on the Internally consistent dataset documentation page.



This section outlines the methodology of the phase equilibria approach. Currently, this page is empty.


Thermocalc references

This page contains an extensive (but not complete) list of references regarding using thermocalc.

Click here to go to the thermocalc references page.