Abstract: A translucent glass brick for use in a building wall as a lighting wall is made of a translucent opal glass in a form of a hollow glass block. The opal glass has an opal appearance and a mean light transmittance of 20-80%, in a glass thickness of 10 mm, for wavelength over a range of 400-700 nm. The opal glass is a lime and chlorine free glass with sodium sulfate and sodium sulfide fine particles dispersed therein for diffusing light transmitting through the glass. The opal glass essentially consists, by weight, of SiO.sub.2 60.0-70.0%, Al.sub.2 O.sub.3 7.0-11.0%, B.sub.2 O.sub.3 1.0-5.0%, BaO 0-3.0%, ZnO 1.0-5.0%, Na.sub.2 O 15.0-21.0%, SO.sub.3 0.3-1.0%, and F.sub.2 0-2.0%.