μεσομέλας
From LSJ
τοῦ εἰδέναι χάριν ἡ πραγματεία → knowledge is the object of our inquiry, the aim of our investigation is knowledge
English (LSJ)
name of a precious stone, Plin.HN37.174.
Greek (Liddell-Scott)
μεσομέλας: ὁ, εἶδος λίθου τιμίου, Plin. h. n. XXXVII, 63.