opal (a mineral consisting, like quartz, of silica, but inferior to quartz in hardness and specific gravity)
Probably borrowed from French opale, from Latin opalus, from Byzantine Greek ὀπάλλιος (opállios), from Sanskrit उपल (upala).
Esercitati a parlare e a memorizzare " opaal " e molte altre parole e frasi in olandese .