1(3 SIE WILLIAM CKOOKES ON SCANDIUM. 



Scandium I found in some of my fractions, but only in small quantities. A few 



years ago I commenced an examination of all the obtainable rare-earth minerals, in 

 order to see if any of them showed more than a trace of scandium. The minerals 

 examined were : 



^Eschynite Homolite Thalenite 



Allanite Keilhauite Thorianite 



Alvite Knopite Thorite 



Auerlite Koppite Thorogummite 



Baddeleite (Ceylon) Lanthanite Tscheffkinite 



Bastnasite Monazite Tysonite 



Broggerite Mosandrite Urdite 



Cerite Orangite Wiikite 



Cleveite Orthite Xenotime 



Columbite Polycrase Yttergarnet 



Cryptolite Pyrochlore Yttrialite 



Eudialite Rhabdophaiie Yttrocerite 



Euxenite Samarskite Yttrogummite 



Fergusonito (Ceylon) Scheelite (Bohemia) Yttrotantalite 



Fergusonite (Ytterby) Scheelite (New Zealand) Yttrotitanite 



Fluocerite Schorlomite Zirkelite (Ceylon, sp. gr. 5'0) 



Gadolinite Sipylite Zirkelite (Ceylon, sp. gr. 4-42) 



Hielmite Tantalite 



Of these minerals scandium was detected in auerlite, cerite, cryptolite, keilhauite, 

 koppite, mosaiidrite, orangite, orthite, pyrochlore, thorianite, thorite, urdite, and 

 wiikite. But while the other minerals contained less than O'Ol per cent, of scandium, 

 wiikite was found to contain more than one hundred times that amount. 



Wiikite is a black amorphous mineral found with monazite in a felspar quarry at 

 Impilaks, Lake Ladoga, Finland. It is named after Professor WllK, of Helsingfors 

 (' Min. Mag.,' vol. xiii., p. 379). 



I have compared wiikite with a large number of typical rare-earth minerals, and in 

 appearance I find it most resembles yttrotantalite. A thin section under the microscope 

 looks like solidified mud. It is quite amorphous, breaks with a conchoidal fracture, 

 shows no crystalline structure, and has no action on polarised light. 



Wiikite is somewhat radio-active. A fragment was laid on a sheet of 

 sensitive film opaque black paper intervening for ninety-five hours. Subsequent 

 development revealed a good impression, about equal in strength to what would be 

 given by pitchblende in twenty-four hours. The image was not uniform, and at one 

 point radiation had spread from the mineral over the adjacent part of the sensitive 

 film. 



The specific gravity of wiikite is 4 '85. Its hardness is 6. It is infusible before the 

 blowpipe. It is imperfectly attacked by strong mineral acids and breaks up easily 

 when fused with potassium bisulphate. Heated to full redness in a silica tube it 

 gives off helium, water, and a distinct amount of sulphuretted hydrogen, followed by 



