1911 Encyclopædia Britannica/Yttrium
YTTRIUM [symbol, Y; atomic weight, 89.0 (O = 16)], a metallic chemical clement. In its character yttrium is closely allied to, and in nature is always associated with, cerium, lanthanum, didymium and erbium (see Rare Earths). For the preparation of yttrium compounds the best raw material is gadolinite, which, according to König, consists of 22.61% of silica, 34.64 of yttria, Y2O3, and 42.75 of the oxides of erbium, cerium, didymium, lanthanum, iron, beryllium, calcium, magnesium and sodium. The extraction (as is the case with all the rare earths) is a matter of great difficulty. Metallic yttrium is obtainable as a dark grey powder by reducing the chloride with potassium, or by electrolysing the double chloride of yttrium and sodium. It decomposes water slowly in the cold, and more rapidly on heating. Yttria, Y2O3, is a yellowish white powder, which at high temperatures radiates out a most brilliant while light. It is soluble, slowly but completely, in mineral acids. It is recognized by its very characteristic spark spectrum. Solutions of yttria salts in their behaviour to reagents are not unlike those of zirconia. The atomic weight was determined by Cleve.