A proportion used in determining the dimensional relationship of a representation to that which it represents: a world map with a scale of 1:4,560,000. b. A calibrated line, as on a map or an architectural plan, indicating such a proportion.
Yttria (yttrium oxide, Y 2 O 3), was discovered by Johann Gadolin in 1794 in a mineral called gadolinite from Ytterby. Ytterby is the site of a quarry in Sweden which contains many unusual minerals containing erbium, terbium, and ytterbium as well as yttrium.
Yttrium is a soft, silvery metal. Yttrium usually exists as a trivalent ion, Y 3+ , in its compounds. Most of its compounds are colorless. Yttriumâs properties are very similar to those of the rare earth elements of the lanthanide series.