TY JOUR TI Estimation of volumetric content of phases from random cross sections KW stereological principle KW phase ratio KW thin sections KW polished sections KW three-dimensional modelling JO Vestnik of geosciences AU Zhuravlev, A.V. PY 2025 IS 0 PB FSBI FIC "Komi Scientific Center of the Ural Branch of the Russian Academy of Sciences"