Iodine by mass action due to the precipitation of the insoluble salt. Iodine is the least abundant of the stable halogens, comprising only 0.46 parts per million of Earth's crustal rocks (compare: fluorine 544 ppm, chlorine 126 ppm, bromine 2.5 ppm). Among the eighty-four elements which occur in significant quantities (elements 1–42, 44–60, 62–83, and 90–92), it ranks sixty-first in abundance. Iodide minerals are rare, and most deposits that are concentrated enough for economical extraction are iodate minerals instead. Examples include lautarite, Ca(IO), and dietzeite, 7Ca(IO)·8CaCrO. These are the minerals that occur as trace impurities in the caliche, found in Chile,
Chlorine pentafluoride with water to produce chloryl fluoride and hydrogen fluoride: It is also a strong fluorinating agent. At room temperature it reacts readily with all elements (including otherwise "inert" elements like platinum and gold) except noble gases, nitrogen, oxygen and fluorine. Chlorine pentafluoride Chlorine pentafluoride is an interhalogen compound with formula ClF. This colourless gas is a strong oxidant that was once a candidate oxidizer for rockets. The molecule adopts a square pyramidal structure with C symmetry, as confirmed by its high-resolution F NMR spectrum. Some of the earliest research on the preparation was classified. It was first prepared by fluorination