D_TEXTBLOCK_TEXT Beryllium is a non-magnetic, lightweight, steel gray metal. It is resistant to corrosion under normal conditions, but is affected by oxygen and nitrogen at high temperatures, and is also affected by some acids at room temperature. It is expensive and is toxic if inhaled or ingested. Beryllium is used in precision mirrors and instruments, radiation detectors, X-ray windows, aircraft brakes, and rocket nozzles.