Pottery vessels painted in powdered blue pigment make their appearance during the mid Eighteenth Dynasty. According to Lacovara (p. 236 in Freed, Markowitz, D'Auria, eds., op. cit.) the pigment was derived either from cobalt deposits in the desert oases or from imported glass ingots that were ground down. Vessels decorated with human, animal and plant forms are depicted in tomb scenes, and although these were likely of metal, they inspired the more humble pottery versions. Lacovara further explains that the young gazelle and the ankh "were associated with rebirth and rejuvenation, a theme that continued to be popular during the Amarna period."