Editing Erbium (section)

== Occurrence ==
[[File:MonaziteUSGOV.jpg|thumb|left|Monazite sand]]
The concentration of erbium in the Earth crust is about 2.8&nbsp;mg/kg and in seawater 0.9&nbsp;ng/L.<ref name="patnaik">{{cite book | last =Patnaik | first =Pradyot | date = 2003 | title =Handbook of Inorganic Chemical Compounds | publisher = McGraw-Hill | pages = 293–295| isbn =978-0-07-049439-8 | url= https://books.google.com/books?id=Xqj-TTzkvTEC&pg=PA293 | access-date = 2009-06-06}}</ref>  (Concentration of less abundant elements may vary with location by several orders of magnitude<ref name=CRC>Abundance of elements in the earth’s crust and in the sea, ''CRC Handbook of Chemistry and Physics,'' 97th edition (2016–2017), p. 14-17</ref> making the relative abundance unreliable). Like other rare earths, this element is never found as a free element in nature but is found in [[monazite]] and [[bastnäsite]] ores.<ref name="emsley" /> It has historically been very difficult and expensive to separate rare earths from each other in their ores but [[ion-exchange]] chromatography methods<ref>Early paper on the use of displacement ion-exchange chromatography to separate rare earths: {{cite journal | last1 = Spedding | first1 = F. H. | last2 = Powell | first2 = J. E. | date = 1954 | title = A practical separation of yttrium group rare earths from gadolinite by ion-exchange | journal = Chemical Engineering Progress | volume = 50 | pages = 7–15 }}</ref> developed in the late 20th century have greatly reduced the cost of production of all rare-earth metals and their [[chemical compound]]s.<ref>{{Cite journal |last=El Ouardi |first=Youssef |last2=Virolainen |first2=Sami |last3=Massima Mouele |first3=Emile Salomon |last4=Laatikainen |first4=Markku |last5=Repo |first5=Eveliina |last6=Laatikainen |first6=Katri |date=2023-04-01 |title=The recent progress of ion exchange for the separation of rare earths from secondary resources – A review |url=https://www.sciencedirect.com/science/article/pii/S0304386X23000294 |journal=Hydrometallurgy |volume=218 |pages=106047 |doi=10.1016/j.hydromet.2023.106047 |issn=0304-386X|doi-access=free }}</ref>

The principal commercial sources of erbium are from the minerals [[xenotime]] and [[euxenite]], and most recently, the ion adsorption clays of southern China. Consequently, China has now become the principal global supplier of this element.<ref>Asad, F. M. M. (2010). ''Optical Properties of Dye Sensitized Zinc Oxide Thin Film Deposited by Sol-gel Method'' (Doctoral dissertation, Universiti Teknologi Malaysia).</ref> In the high-yttrium versions of these ore concentrates, yttrium is about two-thirds of the total by weight, and erbia is about 4–5%. When the concentrate is dissolved in acid, the erbia liberates enough erbium ion to impart a distinct and characteristic pink color to the solution. This color behavior is similar to what Mosander and the other early workers in the lanthanides saw in their extracts from the gadolinite minerals of Ytterby.{{Citation needed|date=September 2024}}