A soft, silvery, easily oxidized metallic element that ignites spontaneously in air when finely divided. Strontium is used in pyrotechnic compounds and various alloys, and as a coating on cathode-ray tubes and related display devices to block x-ray emission. Atomic number 38; atomic weight 87.62; melting point 777°C; boiling point 1,382°C; specific gravity 2.64; valence 2. See Periodic Table.