  We study the single-vortex solution of the t-J model within
resonating-valence-bond (RVB) mean-field theory. We find two types of vortex
cores, insulating and metallic, depending on the parameters of the model. The
pairing order parameter near both cores have $d_{x^2 -y^2}+i\eta d_{xy}$
symmetry. For some range of $t/J$ the calculated tunneling spectrum of the
metallic vortex core agrees qualitatively with the STM tunneling data for
BSCCO.
