Celestine Geode

SrSO4 - Mohs Hardness: 3 - 3½. Celestine is an attractive mineral consisting of stronitum sulfate that forms in well-shaped crystals with a distinctive blue color. While pure Celestine is colorless, various impurities give this mineral a wider range of colors, especially the unique blue color. Celestine geodes with sky-blue crystals are well-known and abundant from Madagascar. Celestine is the principal source of the element stronitum commonly used in fireworks and in various metal alloys.http://utdr.utoledo.edu/rock-mineral/1063/thumbnail.jp