For general use, fused quartz is unreactive, including when exposed to most acids, metals, chlorine and bromine at ordinary temperatures. It is slightly attacked by alkaline solutions, the reaction rate increasing with temperature and concentration of solution. Phosphoric acid will attack fused quartz at temperatures about 150 °C. Hydrofluoric acid alone will attack at all temperatures. Carbon and some metals will reduce fused quartz; basic oxides, carbonates, sulfates, etc., will react with it at elevated temperatures.