We performed ammonothermal synthesis of a self nucleated GaN seed and grew crystalline GaN on the seed in the presence of an NH4F-based mineralizer. Our results suggest that spontaneously nucleated, high quality GaN crystals can be obtained by recrystallization of polycrystalline hydride vapor phase epitaxy (HVPE) GaN under acidic ammonothermal conditions. We achieved average growth speeds of up to 410 and 465 mu m/day on the c- and m-directions, respectively, after four consecutive crystal growths of GaN on a self nucleated seed. GaN crystals grown on an HVPE seed and on a sell nucleated seed had comparable crystal quality, judged from room temperature photoluminescence measurements. (C) 2014 Elsevier B.V. All rights reserved.