“ YTTERBIUM (Neo-Ytterbium) [symbol, Yb; atomic weight, 172.0 (O = 16) ] , a metallic chemical element belonging to the rare earth group. Mixed with scandium it was discovered by Marignac in gadolinite in 1878 (see Rare Earths) . The oxide, Yb2O3, is white and forms colourless salts; the crystallized chloride, YbCl3·6H2O, forms colourless, deliquescent crystals ”