Celestine

Celestine is a striking mineral that forms in well-shaped crystals with a soft blue hue. The crystals can be a solid blue or display zones of lighter and darker blue. While pure Celestine is actually colorless, various impurities give it a range of colors—especially its signature celestial blue. Large, deep sky-blue Celestine geodes from Madagascar are well-known and abundant.

Celestine is similar in structure to Barite and can sometimes partially replace it; a single crystal may even contain both minerals. Its name comes from the Latin word "caelestis," referring to its typical sky-blue color..

This mineral appears as crystals in geodes and can also be found in sedimentary rocks, as fibers, or in river, lake, and ocean beds. Often growing alongside Gypsum, Anhydrite, and Halite, Celestine is present in small amounts worldwide. The light blue specimens that inspired its name are especially common in Madagascar and Sicily, Italy, although it can also occur in colors like colorless, white, pink, pale green, pale brown, and black.