Kalmar “Optic flint” yawanci tana nufin nau’in gilashin da aka yi daga haɗin siliki da gubar gubar. Ana amfani da wannan nau'in gilashin sau da yawa wajen kera lenses da sauran kayan aikin gani, kuma an san shi da babban ma'aunin refractive da iya tarwatsa haske cikin launukansa. "flint" na iya nufin kowane nau'in abu mai wuya, mai ɗorewa, da mara faɗuwa wanda ake amfani da shi wajen kera kayan aiki ko wasu abubuwa. Duk da haka, a cikin mahallin na'urar gani, "Optic flint" musamman yana nufin nau'in gilashin da ke da kaddarorin da aka kwatanta a sama.