Аннотация:The viscosity of heterogeneous basalt melts was estimated using a new structural – chemical model for reliable calculations of the temperature, concentration, phase, and pressure dependences of magma viscosity (Persikov, Bukhtiyarov, 2020). It was made in the temperature range of 1100-1300 oC, hydrogen pressures of 10-100 MPa, and metal phase concentrations up to 10 vol. %, crystal concentrations up to 30 vol. % and bubble concentrations up to 40 vol.%. It is found that the concentration of crystals, the metal phase, and bubbles in the melt has the greatest influence on the viscosity of such melts. For example, when their total concentration in the melt is equal to 80 vol. %, the viscosity of the basalt melt increases by almost an order of magnitude in the full range of the specified temperatures.