TgJ Is34:9 :וְיִתהַפכוּן נַחלַהָא דְרוֹמֵי לִזפָא וְעַפרַה לְגוּפרֵיתָא‏ : the rivers of Rome shall be turned to pitch [MT לְזֶפֶת] and its dirt to sulphur
See the entire entry for zpˀ n.m. pitch