88 GEORGE I. FIN LAY 



In this calculation the available SiO^ is 309, the CaO 241, and the 



(MgFe)O, 146. 



z 

 Therefore (i) 2Jc:+3}' + -=309 



(2) x+/\y =241 

 and (3) x+z =146. 

 From (2), multiplying by 2, 



2X-\-?>y = ^S2; 



(i) 2„T+33'+^=309; 



subtracting ^y — =173 



or lo}'— 2=346. 



Again (2) a; +4}' = 241 



(3) x+z=i^6; 



subtracting 4);— 2 = 95 



lo)'— 2=346 



43,-2=95 



y=A2, ackermanite 

 5C=73, new diopside 

 z= 73, new olivine. 



With silica still lower than in Analysis Q we make such a calcula- 

 tion as is given in Analysis R. Here, after the assignment for ilmenite 

 the K2O, 79 units, is held out with equal Al2 03.Na2 0, takes AI2O3 

 as far as it is available (17), and SiO^ for nephelite. Extra NajO, 

 9, takes^FcjOg and SiOa for acmite. Fe2 03 remaining takes equal 

 FeO for magnetite. All the CaO, 296 units, is calculated as acker- 

 manite, and ^MgO and FeO remaining over take SiOa for olivine. 

 Silica is left equal to 204 units. This is distributed with the 79 

 K2O.AI2O3 held out (ante), between leucite and kaliophilite (kp), 

 K20.Al203.2Si02. The equations are 



:x;-|-^=K20 

 ^x+2y='S)i02 



where jc=the number of molecules of leucite 

 and y=i\i& number of molecules of kaliophilite. 

 (i) x+y=^(), K2O 

 (2) 4X-\-2y=20/[, SiOa. 

 From (i) 2X-\-2y=i$9> 

 2Jc;=46 



x=23, leucite molecules 

 ;y=56, kaliophilite molecules. 



