Vol. 56.] MINERALS CONTAINING RARE ELEMENTS. 521 



27. On the Discovery and Occurrence of Minerals containing 

 Rare Elements. By Baron Adolf Erik Nordenskiold, 

 F.M.G.S. (Bead April 4th, 1900.) 



The remarkable discoveries of recent years with regard to the com- 

 position of the air, and the discovery of several new gaseous elements, 

 have again unexpectedly directed general attention to those Scandi- 

 navian minerals which contain rare earths and acids. It will, there- 

 fore, be the more proper to give here a brief sketch of the discovery 

 of these minerals, as most of them were not only first found in 

 Sweden, Norway, Finland, or Greenland, but also first described by 

 Swedish observers in the Transactions of the Boyal Swedish Academy 

 of Sciences. In doing this I shall have an opportunity of correcting 

 some mistakes and inadvertencies of foreign investigators as to the 

 history of these discoveries, and of showing the groundlessness of 

 certain geological or cosmological speculations which have been 

 induced by the unexpected observation that the new gases, when 

 occurring in the crust of our planet, seem to be particularly associated 

 with minerals containing rare earths. 



A mineral containing earths of this kind is mentioned for the 

 first time in mineralogical literature in a paper by Axel Er. Cron- 

 stedt, entitled 'Experiments & Trials made on Three Iron-ores,' 

 and printed in the K. Svenska Vetenskapsakademiens Handlingar 

 in 1751. One of these supposed iron-ores consisted of a substance 

 in which there is no iron at all, namely, the greyish-white heavy 

 mineral from Bispberg in Dalecarlia which is now called scheelite, 

 and from which, thirty years later, Scheele first separated the oxide 

 of the important element wolfram. This element is still called 

 tungstene by French chemists, from the name Bispberg s 

 tungsten (heavy stone) given by Swedish miners to the mineral 

 in which the oxide was discovered. Another of these ' iron-ores,' 

 Bastnas tungsten, which, according to the quite correct obser- 

 vation of Cronstedt, i contained iron, together with an earth which 

 fuses very slowly to a slag,' is the mineral from which, in the begin- 

 ning of the nineteenth century, Berzelius and Hisinger, and, inde- 

 pendently of them, Klaproth, obtained the oxide or earth of a new 

 substance, cerium. In the years 1839-1842, however, this earth 

 was decomposed by Mosander into the oxides of cerium, lanthanum, 

 and didymium ; and in 1885 the Austrian chemist, Auer von Wels- 

 bach, succeeded in isolating from the didymium-oxide of Mosander a 

 fourth elemant, to which the name praseodidymium was given. 



Thus no less than four out of the seventy or so elements of which 

 the crust of the earth and its gaseous envelope are formed have been 

 discovered in Bastnas tungsten or, as the mineral is now called, 

 cerite. Since then these substances — cerium, lanthanum, didy- 

 mium, and praseodidymium — have also been met with in a number 

 of other minerals chiefly occurring in northern countries. They 



