CHEMICOMINERAL RELATIONSHIPS IN ROCKS 221 



of minerals, may be expressed in the simplest form, as in the fol- 

 lowing list, first by the empyrical formulas, second by the 

 dualistic, the convenience of the latter being apparent when com- 

 parison is made with the chemical composition of the rocks, as 

 expressed in the usual statement of analyses. 



Quartz, - 

 Orthoclase, - 

 Soda-orthoclase, 

 Soda-microline, 

 Albite, - 

 Oligoclase, 

 Andesine, 

 Labradorite, 

 Anorthite, - 

 Leucite, - 



Nephelite, - 



Soda-nephelite, 



Sodalite, 



Hauynite, 



Nosite, 



Muscovite 



Biotite, 



Olivine, - 



Pyroxe7ies 

 f Enstatite, 

 I Hypersthene, 

 I Diopside, 



•{ Salite, - 



Augite, - 



l^Acmite, 



Amfthiboles 



\ 



I Hornblende, 



| Arfvedsonite, 



| Riebeckite, 

 Magnetite, 



- Si0 2 

 KAlSi 3 8 



— (K ) Na)AlSi 3 8 



- NaAlSi 3 8 



\ m(NaAlSi 3 8 ) 

 \ n (CaAl 2 Si 2 8 ) 



CaAl 9 Si 2 8 



- KAlSi 2 6 

 KAlSi 2 6 



n (NaAlSi0 4 ) 

 NaAlSi0 4 

 Na 4 (AlCl)Al 2 Si 3 



Si0 2 

 K 2 O.Al 2 3 .6Si0 2 



(K,Na) 2 O.Al 2 3 .6Si0 2 



Na,O.Al 2 Oo.6Si0 2 



CaO.Al 2 3 2Si0 2 

 K 2 O.Al 2 3 .4Si0 2 



Na 2 O.Al 2 3 .2SiO, 

 3[Na 2 O.Al 2 3 .2Si0 2 ]+2NaCl 

 Na 2 Ca(NaS0 4 .Al)Al 2 Si 3 12 3[Na 2 O.Al 2 3 .2Si0 2 ]+2CaS0 4 

 Na 4 (NaS0 4 .Al)Al 2 Si 3 1 , 3[Na 2 O.Al 2 3 .2Si0 3 ]+2NaS0 4 

 KH 2 Al 3 Si 3 12 (K,H),O.AU0 3 .2Si0 2 



(H,K) 2 (Mg,Fe) 2 (Al,Fe) 2 

 (Si0 4 ) 3 



( 2[(H,K)(Al,Fe)Si0 4 ] 

 \ (Mg,Fe) 2 Si0 4 

 (Mg,Fe) 2 Si0 4 



2[(H,K) 2 0.(Al,Fe) 2 3 .2Si0 2 J 



2(Mg,Fe)O.Si0 2 

 2(Mg,Fe)O.Si0 2 



Mg 2 Si 2 6 



- (Mg,Fe) 2 Si 2 6 

 CaMgSioO G 



- Ca(Mg,Fe)Si 2 6 

 Ca(Mg,Fe)Si,0 6 

 (Mg,Fe)(Al,Fe) 2 Si0 6 



NaFeSi,O fi 



Ca(Mg,Fe) 3 Si 4 12 

 (Mg,Fe) 2 (Al,Fe) 4 Sio0 1 o 

 Na 2 ,Al 2 Si 4 12 

 (Na 2 ,Ca,Fe) 4 Si 4 12 

 (Ca,Mg) 2 (ALFe) 4 Si 2 12 

 Na 2 Fe,Si 4 12 

 FeSi0 3 

 Fe s 4 



MgO.Si0 2 



(Mg,Fe)O.Si0 2 



CaO.Mg0.2Si6 2 



CaO.(Mg,Fe)0.2Si0 2 

 CaO(Mg,Fe)0.2Si0 2 

 (Mg,Fe)0.(Al,Fe) 2 3 .Si0 2 



Na 2 O.Fe 2 3 ,4Si0 2 



( Ca0.3(Mg,Fe)0.4Si0 2 



\ (Mg,Fe)0.(Al,Fe) 2 3 .Si0 2 



( Na 2 O.Al 2 3 .4Si0 2 



(Na 2 ,Ca,Fe)O.Si0 2 



(Ca,Mg)0.(Al,Fe) 2 3 .Si0 2 



Na 2 O.Fe 2 3 .4Si0 2 

 FeO.SiO, 



From this it will appear into how many different molecules 

 any chemical element many enter. In order to simplify the 



