This reaction distinguishes the members of the yttria group from most of the other earths.
yttria may be obtained from gadolinite by a similar process to that by which glucina is extracted from the beryl.
These crude earths, yttria and ceria, have supplied most if not all of the “rare earth” metals.
(c.) yttria (YO) occurs only in a few rare minerals, and usually in company with terbium and erbium.
yttria is an exceedingly complex mixture, which has been decomposed, yielding as an intermediate product terbia.