254 



Gires fparks, 



Sp. gravity. 

 Locality and 

 gangue, &c. of 

 yttrotantalite. 



Size and frac- 

 ture of the 

 xnafies. 



Hardnefs. 



Powder. 



Not magnetical 



Sp.gr. 



On gadolinite. 



PROPERTIES OE THE EARTH YTTRIA. 



It is fufficiently hard to give fparks with the fteel. 



He did not remark whether it is attracted by the magnet* 



Itsfpecific gravity is 7,953. 



The yttrotantalite is found in the fame place and in the fame 

 gangue as gadolinite. Klaproth fays, that the latter is found 

 incrufted in a mafs of granite ; but though the conftituent 

 parts of granite are occasionally found with it, it is not thelefs 

 infilled that feldfpar is its true gangue, as is clearly feen in the 

 inftances of the great quarry at Ytterby. The mica and quartz 

 found in it form diftinct parts, and do not enter into combina- 

 tion with the feldfpar ; (he fpeaks only of the maffes of the 

 principal rock, without difputing the poffibility of particles of 

 the three fubftances being found mixed) ; but in general it is a 

 rock of feldfpar interfered by large veins of mica in a direction 

 afmoft perpendicular; and the gadolinite and yttrotantalite 

 are to be fought near thefe veins. The firft is commonly 

 found attached to one fide of a vein of filvery mica, and the 

 reft of its mafs enveloped with feldfpar. The fecond is never 

 found immediately adherent to mica. The maffes or kidnies 

 which it forms, are enveloped with a thin cruft of feldfpar, 

 feparated from the general mafs by flight layers of a greyifti 

 black mica. The gangues charged with thefe kidnies are 

 feldom infulated : They are found in clutters, feparated from 

 the principal rock and from one another by fimilar coatings 

 of mica. Thefe fubftances are generally thus difpofed by na- 

 ture, and it is very feldom that they are found tUffeminated in 

 grains in the rock of feldfpar. 



The largeft maffes he has found of the ore of yttrotantalium 

 were not of the fize of a nut. Its fracture is granulated, of 

 the black colour of iron, with a metallic brilliancy. 



Its hardnefs is not confiderable; it may be fcraped with a 

 knife, though difficultly. 



When in powder it is ofagreyifh colour. 



The magnet does not attract it. 



Its fpecific gravity was found to be 5>1.30; but as no fpeci- 

 men was found totally free from feldfpar, it was fufpe&ed that 

 its real weight is more confiderable. 



The abridger concludes his extract by giving an outline of 

 that part of M. Ekeberg's Memoir, which treats of the analyfis 

 of gadolinite and the comparifon of yttria with glucine, which 

 feveral writers have affirmed to be of the fame nature. 



Gadolinite 



