Alkaline molybdate crystals are proved to be promising bolometric materials for rare events study, particularly, for neutrinoless double-beta decay search. In addition to high molybdenum ratio, Li2MoO4 and Na2Mo2O7 crystals exhibit ultra-low radiation background, luminescence at low temperatures, considerable light yield and high energy resolution. In this work dependence of crystal faceting on the value of Jackson criterion was shown. Growth mechanisms of Li2MoO4 and Na2Mo2O7 crystals and their influence on crystal morphology were studied, representative facet families were determined. Three cleavage planes (0 1 0), (0 0 1) and (0 2 1) were identified in Na2Mo2O7 crystals grown in [0 1 0] direction.