Strontium
Strontium (Sr) is the 15th most abundant element in the earth’s crust. Only two minerals, however—celestite and strontianite—contain strontium in sufficient quantities to make recovery practical, and these minerals are found predominantly in sedimentary rocks. Strontium is a silvery-yellow, metallic element. Strontium belongs to a group of elements known as the alkali earth metals. Like other alkali metals, it is chemically active and will react with both air and water.
Type
Element (Minerals/Ores of)
Mineral Classification
carbonate (stronianite), sulfate (celestite)
Chemical Formula
SrCO3 (stronianite), SrSO4 (celestite)
Streak
White
Mohs Hardness
3.5 (stronianite), 3-3.5 (celestite)
Crystal System
orthorhombic
Color
Colorless, white, gray, light yellow, green or brown; colorless in transmitted light colorless, white, gray, light yellow, green or brown; colorless in transmitted light (stronianite)
Colorless, white, pale blue, pink, pale green, pale brown, black (celestite)
Luster
vitreous, resinous, greasy (stronianite), vitreous, pearly (celestite)
Fracture
Uneven
Description
Strontium (Sr) is the 15th most abundant element in the earth’s crust. Only two minerals, however—celestite and strontianite—contain strontium in sufficient quantities to make recovery practical, and these minerals are found predominantly in sedimentary rocks. Strontium is a silvery-yellow, metallic element. Strontium belongs to a group of elements known as the alkali earth metals. Like other alkali metals, it is chemically active and will react with both air and water.
Relation to Mining
Only two minerals, celestite and strontianite, contain strontium in sufficient quantities to make recovery practical. Of the two, celestite is more common in economic deposits. It is similar in structure to barite, the barium sulfate mineral. Strontianite is more desirable of the two common minerals because strontium is used most commonly in the carbonate form and contains more strontium, but few deposits have been discovered that are suitable for economic development.
Uses
Strontium is the element that gives road flares and fireworks a bright red color. Some strontium is used to make special magnets called ferrite ceramic magnets. Strontium was used to make compounds that were applied to the glass picture tubes on color television sets before flat screen TVs became popular. This compound blocked the X-rays created by the picture tube.
