Editing Francium (section)

==Occurrence==
[[File:Pichblende.jpg|thumb|This sample of [[uraninite]] contains about 100,000 atoms (3.7{{e|-17}}&nbsp;g) of francium-223 at any given time.<ref name="nbb" />|alt=A shiny gray 5-centimeter piece of matter with a rough surface.]]
<sup>223</sup>Fr is the result of the alpha decay of [[Isotopes of actinium|<sup>227</sup>Ac]] and can be found in trace amounts in [[uranium]] [[mineral]]s.<ref name="CRC2006" /> In a given sample of uranium, there is estimated to be only one francium atom for every 1 × 10<sup>18</sup> uranium atoms.<ref name="nbb" /> Only about {{convert|1|oz|g}} of francium is present naturally in the earth's crust.<ref>{{Cite book |last=Krebs |first=Robert E. |url=https://books.google.com/books?id=D7LOEAAAQBAJ&dq=%22francium%20hydroxide%22%20existence&pg=PA64 |title=The History and Use of Our Earth's Chemical Elements: A Reference Guide |date=2006-07-30 |publisher=Bloomsbury Publishing USA |isbn=978-0-313-02798-7 |language=en}}</ref>