Szaibelyite ore is an important boron mineral used for producing boron compounds. Sodium metaborate dihydrate can be prepared through leaching of the szaibelyite ore in NaOH solution and the leaching liquor mainly consists of NaBO2 and NaOH. In this work, the induction time for sodium metaborate dihydrate crystallized in NaOH solution from 30 to 50 degrees C was systematically investigated. The primary nucleation and growth mechanism were determined on the basis of the induction time measurements. The crystals of various morphologies under different crystallization conditions were obtained: the rodlike crystals preferred to form at low temperature, while the plate-like crystals formed at high temperature; when the crystallization temperature was 30 degrees C, the flat rod-like crystals formed at low supersaturation, while the slim rod-like crystals formed at high supersaturation. Finally, the growth mechanism of the sodium metaborate dihydrate was identified with various models and the 2D nucleation-mediated model gave satisfactory fitting results. (C) 2015 Elsevier B.V. All rights reserved.