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.