Scientific Name: Strontium sulfate or Barium sulfate
Group: Sulfates
Chemical composition: SrSO4
Colors: Colorless, white, red, green, blue, or brown
Hardness: 3 to 3.5
Formation: Orthorhombic crystal; Tabular form.
Principal Sources: Madagascar, Mexico, Italy, Canada, US.
Special Notes: Along with strontianite, celestite is the principal source of strontium, which is used to create the red color in fireworks, signal flares, and tracer bullets.