MAGMATIC DIFFERENTIATION OF IGNEOUS ROCKS 443 
Noritic Eutectic LINE BETWEEN PLAGIOCLASE 
AND HYPERSTHENE 
I ali Til 
45 Hyp: 40 Hyp: 35 Hyp: 
55 An;sA bisOr, 60 Ane2Ab320re 65 AnyAbyOre 
SHD)p o 3 oece: Ganley ee lee een areemae 49.7 51.9 54.5 
PMO MERE ce oie cocoa tenets, S eet 12) 03 19.1 18.8 
HELO MMi cis ctamecavee ete nee I.1 TSO) 0.9 
re > 04 RSIS eR ee eet ein » it 8.1 EEL 
IWIZO). 2 scofdiointae sees ae ces 9.3 8.3 1 
(CRO). 3 o ode Gteten ete nae eee eee aes 9.9 8.7 sli 
IN BAO), 5: 6 o-g GneRaREE arNeeae 2 DB 3.6 
TSAO), 0 9 Sg Oa ee eae 0.4 0.6 On, 
For the diallage of the gabbros we assume: 40 CaMgSi.O¢, 36 CaFeSi,0¢ 
7 MgAl,sSi0¢, 11 FeFe.SiOe, 6 MgSiO;=47.5 per cent SiO., 3.8 Al,O;, 6 Fe.0,, 
73.1 FeO, 11.1 MgO, 18.5 CaO. And for the augite of the diorite: 
52 CaMgsi,0¢, 34 CaFeSi.0¢, 3 MgALSiO«, 6Fe Fe2SiOe, 5 Mg SiO;= 50.45 per 
Gent S107, 1.65 AlLO,, 3.3 Fe.0,, 11.3 FeO, 12.2-MgO, 21.1 CaO. 
GABBROIDIC EuTEcTIC LINE BETWEEN Drioritic Eutectic LINE BETWEEN 
PLAGIOCLASE AND DIALLAGE PLAGIOCLASE AND AUGITE 
a) Ild IIIb IV V VI 
45 Diallage: 4o Diallage: 35 Diallage: 33 Augite: 27 Augite: 20 Augite: 
55 AnzsA bisOr, | 60 AnezAb320re | 65 AngzAby7Ore |67 Ang2zAbgsOrz0]73 An3zA bs6Orz2}80 Anz2A besOrra 
Sire 48.0 50.5 83.2) Be eit Ba 5 60.2 
ALO; . 19.9 OE] 19.3 18.5 18.5 18.8 
Fe,0,. 2G 2.4 DW 1.1 1.0 ©o7/ 
FeO. . 5-9 52 4.6 BaF B50) QB 
MgO. 550 4.4 2.9 4.0 BoB 2.4 
CaO.. 16.9 I4.9 12.6 12.6 10.4 7.8 
Na.O. Toe Bok BHO 3.8 4.8 6.2 
K.O.. 0.4 0.6 0.7 1.1 ToS 1.6 
In the anchi-eutectic norites or gabbros with rather basic 
plagioclase (Ab,An,), the simultaneous crystallization of plagio- 
clase and pyroxene will commence at about II (or IIb) and be 
finished at about III (or III0), or at still less pyroxene and more of a 
relatively Ab-rich plagioclase, about equal to IV. And in the 
medium-basic anchi-eutectic diorites the simultaneous crystalliza- 
tion of plagioclase and pyroxene will commence about at IV 
(or between IV and V) and finish at about VI. 
[To be continued] 
