Germanium monoxide
Germanium monoxide is a chemical compound of germanium and oxygen. It can be prepared as a yellow sublimate at 1000 °C by reacting GeO2 with Ge metal. The yellow sublimate turns brown on heating to 650 °C. GeO is not well characterised. It is amphoteric, dissolving in acids to form germanium salts and in alkali to form "trihydroxogermanates" or "germanites" containing the Ge3− ion.