Neodymium and Praseodymium Oxides: Rare Earths Separated into Coloured Bands on a Bleached Resin Column (Jaffe, US 2,897,050)

The rare earths are so alike that separating them took endless analyses. Jaffe bleached the dark exchange resin with peroxide so the elements show as coloured bands as they wash down the column: neodymium is the violet one, praseodymium the green one, and you simply collect them by eye. Result: 2.48 g of neodymium oxide (a pale blue powder) and 0.81 g of praseodymium oxide from 15 g of monazite oxides in Jaffe's example. Source: Jaffe, US 2,897,050 (Air Reduction, 1959). Not given: purity of the neodymium and praseodymium fractions. Picture drawn by Youblob.