Prof. Bcrzelius on two newly discovered Mineral Specks. &59 



The proportion of the ingredients is 



Yttria, - 62.58. 



Phosphoric acid, with a little fluoric acid, - 33.49. 



Phosphate of iron, with excess of base, - 3.93. 



The corresponding formula is, Y 3 P 2 , analogous to the native 

 phosphate of lime. 



2. Polymign'ite. 



The name of this mineral is derived from croXOs much, and 

 tuywoi I mix, in allusion to the great number of substances of 

 which it is composed. It occurs in more or less regular im- 

 bedded ci'ystals, from a line to upwards of an inch in length, 

 in the zircon syenite of Frederikovarn in Norway. The spe- 

 cimens analyzed were collected by Mr Tank. 



Its regular forms belong to the prismatic system of Mohs 5 

 one of the varieties is represented in Fig. 15, Plate VI. They 

 are generally compressed between T and T, and lengthened in 

 the direction of the axis. The cleavage is very imperfect, though 

 sometimes traces of it are visible parallel to T and M ; the 

 fracture is highly perfect conchoidal. The surface of the 

 crystals is sometimes longitudinally streaked, but possesses a 

 considerable degree of an imperfect metallic lustre, which is 

 still higher in the fracture. Its colour is black ; the streak 

 dark brown, rather paler when the mineral is much commin- 

 uted. It is opaque. The hardness is = 6.5, between quartz 

 and felspar, the specific gravity = 4.806 



Before the blow-pipe it remains entirely unaltered. It does 

 not give out water. To glass of borax, in which it is readily 

 dissolved, it communicated the colours produced by iron, and 

 if it is added in a rather large proportion, the globule may be 

 rendered opaque by flaming, and then it assumes a nearly 

 orange-yellow colour. With tin it yields a reddish-yellow 

 colour. It is dissolved likewise by salt of phosphorus. In 

 the reducing flame the globule becomes reddish, and is not 

 altered by the addition of tin. It does not melt with carbonate 

 of soda, but is changed into a reddish-grey mass. It yields 

 traces of tin by reduction. 



Only 0.6*58 grammes could be subjected to the chemical 

 analysis, and it is therefore not to be expected, that from M 



