| http://www.w3.org/ns/prov#value | - where Ln is a low cost lanthanide mixture, being either in a naturally occurring state or a partially separated and unfinished concentrated state, selected from a mixture of at least two, at least three, at least four, or at least five of without limitation, La, Ce, Pr, Nd, and Sm and other lanthanides, with the proviso that if Ln comprises a mixture of only two lanthanides, the mixture is not the
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