Nuclear bomb detonation produces a small amount of local I-131 fallout. Most I-131 distributes over large distances, typically with only 10% making its way to the earth’s surface before undergoing spontaneous radioactive decay to stable xenon-131.
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Fluorite (Wikipedia)Fluorite (also called fluorspar) is the mineral form of calcium fluoride, CaF2. It belongs to the halide minerals. It crystallizes in isometric cubic habit, although octahedral and more complex isometric forms are not uncommon.