An occurence of the rare mineral thaumasite in Turkey is described for the first time. It is found at Girelbelen-Bodrum in veins within xenoliths of carbonate rock in dioritic intrusions. It occurs in a sulfide mineral assemblage similar to those of its other occurences. Its optical and X-ray properties agree well with published data. It is believed to have formed at low temperature (< 300°C) from sulfide-rich solutions.