LSJ
ῶνος, ὁ, a tufa quarry, Tab.Heracl. 1.137. (Lat. tōfus, prob. borrowed from an Italic dialect.)
Liddell-Scott-Jones, Greek-English Lexicon (9th ed., 1940)
Pape
ῶνος, ὁ, der Steinbruch, Tabul.Heracl.
Pape, Griechisch-deutsches Handwörterbuch (3. Aufl., 1914)