Celestine is a strontium sulfate mineral (SrSO4). It is similar to another and more common sulfate mineral barite (BaSO4). Their crystals may be very similar and there is a continuous solid solution between the two. Celestine is the principal source of strontium. The other major strontium-bearing mineral is strontianite (SrCO3) which belongs to the carbonate group, but it isn’t usually exploited as a source of strontium.
The druse from Yates in England. Strontium was released during the dolomitization of originally aragonitic sediments. It was released because dolomite can hold only 200…600 ppm of strontium while aragonite can hold up to 80001. Width of sample 10 cm.
Celestine is mostly found in cavities in dolomites and dolomitic limestone. Tabular crystals are found in hydrothermal veins. It also occurs in evaporite deposits.
Is there anything celestial about celestine as the name seems to suggest? Yes, its crystals may be bluish as the sky because of impurities but this color is actually not very typical. Perhaps the first crystals described were bluish but overall this name is a misnomer. It is usually colorless or white.
Strontium extracted from celestine is used in pyrotechnics. Beautiful bright red colors in the sky of New Years fireworks are caused by strontium compounds. Because of that, the term “celestine” may not be such a misnomer as it first seems to be.
Celestine in a cavity in carbonate rocks in Cyprus. Width of view 25 cm.
1. Deer, W. A., Howie, R. A. & Zussman, J. (1996). An Introduction to the Rock-Forming Minerals, 2nd Edition. Prentice Hall.