What is the X in X-mas?
metallic rare-earth element, 1866, coined in Modern Latin by Swedish chemist Carl Gustaf Mosander (1797-1858) from Ytterby, name of a town in Sweden where mineral containing it was found.
yttrium yt·tri·um (ĭt'rē-əm)
A silvery, ductile, rare-earth element used in various alloys. Atomic number 39; atomic weight 88.905; melting point 1,522°C; boiling point 3,338°C; specific gravity 4.47 (25°C); valence 3.
A silvery metallic element found in the same ores as elements of the lanthanide series. Yttrium is used to strengthen magnesium and aluminum alloys, to provide the red color in color televisions, and as a component of various optical and electronic devices. Atomic number 39; atomic weight 88.906; melting point 1,522°C; boiling point 3,338°C; specific gravity 4.45 (25°C); valence 3. See Periodic Table.
(Y), chemical element, rare-earth metal of transition Group IIIb of the periodic table, used for red phosphors in colour television. Yttrium metal is silvery in colour, ductile, and relatively reactive; turnings of the metal ignite readily in air