Celestite Egg | Crystal & Mineral Celestite, also known as celestine, is a delicate blue mineral containing strontium. Its pale blue colour is so distinctive that it was said in ancient cultures to be pieces of the sky that had fallen down to Earth. It's said that being in its presence will bring calmness and serenity. Maybe this is why I always seem to reach for it at certain times of the month? This beautiful egg weighs 442g and measures 8cm by 6cm.