Thermobar: An open-source Python3 tool for thermobarometry and hygrometry

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Penny Wieser
Maurizio Petrelli
Jordan Lubbers
Eric Wieser
Sinan Ozaydin
Adam Kent
Christy Till


We present Thermobar, a new open-source Python3 package for calculating pressures, temperatures, and melt compositions from mineral and mineral-melt equilibrium. Thermobar allows users to perform calculations with >100 popular parametrizations involving liquid, olivine-liquid, olivine-spinel, pyroxene only, pyroxene-liquid, two pyroxene, feldspar-liquid, two feldspar, amphibole only, amphibole-liquid, and garnet equilibria. Thermobar is the first open-source tool which can match up all possible pairs of phases from a given region, and apply various equilibrium tests to identify pairs from which to calculate pressures and temperatures (e.g. pyroxene-liquid, two pyroxene, feldspar-liquid, two feldspar, amphibole-liquid). Thermobar also contains functions allowing users to propagate analytical errors using Monte-Carlo methods, convert pressures to depths using different crustal density profiles, plot mineral classification and mineral-melt equilibrium diagrams, calculate liquid viscosities, and convert between oxygen fugacity values, buffer positions and Fe speciation in a silicate melt. Thermobar can be downloaded using pip and extensive documentation is available at


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Wieser, P., Petrelli, M., Lubbers, J., Wieser, E., Ozaydin, S., Kent, A. and Till, C. (2022) “Thermobar: An open-source Python3 tool for thermobarometry and hygrometry”, Volcanica, 5(2), pp. 349–384. doi: 10.30909/vol.05.02.349384.
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Received 2022-07-08
Accepted 2022-10-10
Published 2022-11-09
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