A metallic element of the calcium group, always naturally occurring combined, as in the minerals strontianite, celestite, etc. It is isolated as a yellowish metal, somewhat malleable but harder than calcium. It is chiefly employed (as in the nitrate) to color pyrotechnic flames red. Symbol Sr. Atomic weight 87.3.
- A soft, silvery, easily oxidized metallic element that ignites spontaneously in air when finely divided. Strontium is used in pyrotechnic compounds and various alloys. Atomic number 38; atomic weight 87.62; melting point 769°C; boiling point 1,384°C; specific gravity 2.54; valence 2. See Table at element.