4.442. 



334 MR ANDERSON ON THE ANALYSIS OF CAPORCIANITE AND PHAKOLITE. 



Phakolite, which, in its relations before the blowpipe, agrees in all respects 

 with the other zeolites, was analyzed after the foregoing method, with this ex- 

 ception, that the quantity of water was determined simply by the loss of weight 

 sustained at a red heat. The composition was found to be as follows : 



Silicic acid, . 45.628 oxygen contained 23.708. 



Alumina, . 19.480 9 ' 077 1 9 <>21 



Peroxide of iron, 0.431 0.144) 



Lime, . . 13.304 3.737 



Magnesia, . 0.143 0.053 



Potassa, . . 1.314 0.222 



Soda, . . 1.684 0.430 



Water, . . 17.976 15.982. 



99.960 



This constitution has little resemblance to that of chabasie ; for the quantities of 

 oxygen in r, A S and A q, are to each other in chabasie, whose mineralogical 

 formula is r S 2 + 3 A S 2 + 6 A q, as 1 : 3 : 8 : 6, whereas those quantities in pha- 

 kolite are in the relation of 1 : 2 : 5 : 3^. If we assume that the quantity of water 

 has come out too high, which is generally the case when it is determined by the 

 simple loss of weight at a red heat, then the constitution of phakolite would be 

 represented by the mineralogical formula r S 3 + 2AS + 3 A.q, which transformed 

 to the chemical, is 3 r Si + 2 Al Si + 9 H. 



It appears, then, that phakolite belongs to that class of minerals which in 

 the first term contain a tersilicate, and in the second, a simple silicate of the 

 base, along with water. The minerals belonging to this class at present made 

 out are : 



Gigantolite, . . r S 3 + A S + A q r = fe, mg, K.N. 



Harringtonite, i 3 A S + 2 A , f ' = C.N. 



Mesotype, J ' \r = N.C. 



Lehuntite, . . r S" + AS + 3 Ag r = (N.)C. 



Phakolite, . . rS s + 2AS + 3A? r = (C.)K.N. 



Mezolite ,, . . r S s + 3 A s + 3 A , f ^ N + 2 C. 



Scolezite, J . I r = C. 



Pyrargillite, . . r S" + 3 A S + 4 A q r = fe, my, K.N. 



Antrimolite, . . rS s + 5AS + 5Ay r = C.(K.) 



From this table it will be seen that phakolite forms a middle term between le- 

 huntite and mezolite, and differs from them only in the second or alumina term, 

 which in the three minerals stand to each other in the ration of 1, 2, and 3, while 

 the quantities of silicate of the monatomic bases and water are the same in all 

 three. 



