Editing Curium (section)

===Occurrence===
[[File:Ivy Mike - mushroom cloud.jpg|thumb|Several isotopes of curium were detected in the fallout from the ''[[Ivy Mike]]'' nuclear test.]]
The longest-lived isotope, <sup>247</sup>Cm, has half-life 15.6&nbsp;million years; so any [[primordial nuclide|primordial]] curium, that is, present on Earth when it formed, should have decayed by now. Its past presence as an [[extinct radionuclide]] is detectable as an excess of its primordial, long-lived daughter <sup>235</sup>U.<ref>{{cite news |url=https://phys.org/news/2016-03-cosmochemists-evidence-unstable-heavy-element.html |title=Cosmochemists find evidence for unstable heavy element at solar system formation |date=2016 |publisher=University of Chicago |website=phys.org |access-date=6 June 2022}}</ref> Traces of <sup>242</sup>Cm may occur naturally in uranium minerals due to neutron capture and beta decay (<sup>238</sup>U → <sup>239</sup>Pu → <sup>240</sup>Pu → <sup>241</sup>Am → <sup>242</sup>Cm), though the quantities would be tiny and this has not been confirmed: even with "extremely generous" estimates for neutron absorption possibilities, the quantity of <sup>242</sup>Cm present in 1&nbsp;×&nbsp;10<sup>8</sup>&nbsp;kg of 18% uranium pitchblende would not even be one atom.<ref name=ThorntonBurdette/><ref>{{Cite web|url=https://www.livescience.com/39915-facts-about-curium.html|title=Facts About Curium|last=Earth|first=Live Science Staff 2013-09-24T21:44:13Z Planet|website=livescience.com|date=24 September 2013|language=en|access-date=2019-08-10}}</ref><ref>{{Cite web|url=http://www.rsc.org/periodic-table/element/96/curium|title=Curium - Element information, properties and uses {{!}} Periodic Table|website=www.rsc.org|access-date=2019-08-10}}</ref> Traces of <sup>247</sup>Cm are also probably brought to Earth in [[cosmic ray]]s, but this also has not been confirmed.<ref name=ThorntonBurdette>{{cite journal |last1=Thornton |first1=Brett F. |last2=Burdette |first2=Shawn C. |date=2019 |title=Neutron stardust and the elements of Earth |url=https://www.nature.com/articles/s41557-018-0190-9 |journal=Nature Chemistry |volume=11 |issue=1 |pages=4–10 |doi=10.1038/s41557-018-0190-9 |pmid=30552435 |bibcode=2019NatCh..11....4T |s2cid=54632815 |access-date=19 February 2022}}</ref> There is also the possibility of <sup>244</sup>Cm being produced as the [[double beta decay]] daughter of natural <sup>244</sup>Pu.<ref name=ThorntonBurdette/><ref name="Tretyak2002">{{Cite journal
 |last1=Tretyak |first1=V.I. 
 |last2=Zdesenko |first2=Yu.G. 
 |year=2002
 |title=Tables of Double Beta Decay Data — An Update
 |journal=[[At. Data Nucl. Data Tables]] |volume=80 |issue=1 |pages=83–116
 |doi=10.1006/adnd.2001.0873
|bibcode=2002ADNDT..80...83T }}</ref>

Curium is made artificially in small amounts for research purposes. It also occurs as one of the waste products in [[spent nuclear fuel]].<ref>{{cite journal |vauthors = Chaplin J, Warwick P, Cundy A, Bochud F, Froidevaux P |title=Novel DGT Configurations for the Assessment of Bioavailable Plutonium, Americium, and Uranium in Marine and Freshwater Environments |journal=Analytical Chemistry |date=25 August 2021 |volume=93 |issue=35 |pages=11937–11945 |doi=10.1021/acs.analchem.1c01342 |pmid=34432435 |s2cid=237307309 |doi-access=free }}</ref><ref>{{cite journal |vauthors = Chaplin J, Christl M, Straub M, Bochud F, Froidevaux P |title=Passive Sampling Tool for Actinides in Spent Nuclear Fuel Pools |journal=ACS Omega |date=2 June 2022 |volume=7 |issue=23 |pages=20053−20058 |doi=10.1021/acsomega.2c01884 |pmid=35722008 |pmc=9202248 |hdl=20.500.11850/554631 |url=https://doi.org/10.1021/acsomega.2c01884}}</ref> Curium is present in nature in some areas used for [[nuclear weapons testing]].<ref name="lenntech">[http://www.lenntech.de/pse/pse.htm Curium] (in German)</ref> Analysis of the debris at the test site of the [[United States]]' first [[thermonuclear weapon]], [[Ivy Mike]] (1 November 1952, [[Enewetak Atoll]]), besides [[einsteinium]], [[fermium]], [[plutonium]] and [[americium]] also revealed isotopes of berkelium, californium and curium, in particular <sup>245</sup>Cm, <sup>246</sup>Cm and smaller quantities of <sup>247</sup>Cm, <sup>248</sup>Cm and <sup>249</sup>Cm.<ref>{{cite journal|last1=Fields|first1=P. R.|last2=Studier|first2=M. H.|last3=Diamond|first3=H.|last4=Mech|first4=J. F.|last5=Inghram|first5=M. G.|last6=Pyle|first6=G. L.|last7=Stevens|first7=C. M.|last8=Fried|first8=S.|last9=Manning|first9=W. M.|last10=Ghiorso|first10=A.|last11=Thompson|first11=S. G.|last12=Higgins|first12=G. H.|last13=Seaborg|first13=Glenn T.|display-authors=3|title=Transplutonium Elements in Thermonuclear Test Debris|date=1956|journal=Physical Review|volume=102|issue=1|pages=180–182|doi=10.1103/PhysRev.102.180|bibcode=1956PhRv..102..180F}}</ref>

Atmospheric curium compounds are poorly soluble in common solvents and mostly adhere to soil particles. Soil analysis revealed about 4,000 times higher concentration of curium at the sandy soil particles than in water present in the soil pores. An even higher ratio of about 18,000 was measured in [[loam]] soils.<ref name="LA2" />

The [[transuranium element]]s from americium to fermium, including curium, occurred naturally in the [[natural nuclear fission reactor]] at [[Oklo]], but no longer do so.<ref name="emsley">{{cite book|last=Emsley|first=John|title=Nature's Building Blocks: An A-Z Guide to the Elements|edition=New|date=2011|publisher=Oxford University Press|location=New York, NY|isbn=978-0-19-960563-7}}</ref>

Curium, and other non-primordial actinides, have also been suspected to exist in the spectrum of [[Przybylski's Star]].<ref name=gopka08>{{cite journal |last1=Gopka |first1=V. F. |last2=Yushchenko |first2=A. V. |last3=Yushchenko |first3=V. A. |last4=Panov |first4=I. V. |last5=Kim |first5=Ch. |title=Identification of absorption lines of short half-life actinides in the spectrum of Przybylski's star (HD 101065) |journal=Kinematics and Physics of Celestial Bodies |date=15 May 2008 |volume=24 |issue=2 |pages=89–98 |doi=10.3103/S0884591308020049 |bibcode = 2008KPCB...24...89G |s2cid=120526363 }}</ref>