GLASS, GLASS BLANK FOR PRESS-FORMING, OPTICAL ELEMENT BLANK, AND OPTICAL ELEMENT

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PROBLEM TO BE SOLVED : To provide a glass that has a refractive index nd ranging from 1.75 to 1.80 and an Abbe number νd ranging from 47 to 52, can be stably supplied, and can achieve a high production yield. SOLUTION : The glass at least contains La2O3, Y2O3, ZrO2, ZnO and Nb2O5, and one or both of B2O3 or SiO2, and has, in terms of mass%, a total content of 28 to 38% of SiO2 and B2O3, a total content of 48 to 60% of La2O3, Y2O3, Gd2O3, and Yb2O3, a content of less than 3% of Gd2O3, a content of less than 2% of Y2O3, a content of 2 to 14% of ZrO2, a content of less than 1% of WO3, and a total content of 5% or less of MgO, CaO, SrO and BaO, in which a mass ratio ((La2O3+Y2O3)/(La2O3+Y2O3+Gd2O3+Yb2O3)) is 0.94 or more, ((La2O3+Y2O3+Gd2O3+Yb2O3)/(B2O3+SiO2)) is 1.9 or less, (Nb2O5/(La2O3+Y2O3+Gd2O3+Yb2O3+Nb2O5+TiO2+WO3)) is 0.003 or more, (ZnO/(ZrO2+Nb2O5+Ta2O5)) is 0.2 to 1.4, (ZnO/Y2O3) is 0.30 or more, and ((Li2O+ZnO)/(La2O3+Y2O3+Gd2O3+Yb2O3+ZrO2+Nb2O5+Ta2O5)) is 0.11 or less; and the glass has a refractive index nd ranging from 1.75 to 1.80 and an Abbe number νd ranging from 47 to 52. SELECTED DRAWING : None COPYRIGHT : (C)2016, JPO&INPIT