GeO₂; melting point, 1,115 degrees C. This oxide is a glass former and provides some unique properties; e.g., greater dispersion, lower melting temperature, and higher transmissivity for infrared radiation. Some germanium oxide complexes and solid solutions have ferroelectric properties. Colorless; sp gr, 4.228 (at 25 degrees C); hexagonal; soluble in alkalies; and slightly soluble in acids and in water. Used as an ingredient of special glass mixtures.