Tlif Pi'trographjj of thf. Intrusive Diabase. 



95 



THE CUKMICAL COMPOSITIONS OF THE DIABASE. 



The chemical compositions of the diabase of the colony are shown in 

 the followini^ analyses : — 



Specific gra^'ity 



Silica 



Alumina 



Iron peroxide 



Iron protoxide 



Magnesium oxide . . . 



Calcium oxide 



Sodium oxide 



Potassium oxide ... 



Water 



Carbonic anhydride 



Titanium oxide 



Phosphoric anhydride 



Chlorine 



Iron sulphide 



Cobalt oxide 



Manganese oxide . . . 



Barium oxide 



Copper oxide 



Lr^ad oxide ... 



Potaro Rivei'. 



Dykes in 

 .Sandstone. 



2-97 



52-62 

 16-75 

 2-72 

 7-91 

 5-98 

 10-19 

 2-39 

 0-25 

 0-80 

 0-04 

 0-40 

 0-005 



0-002 



trace. 



trace. 



100-057 



Dykes in 

 Lower 

 Potaro. 



2-9; 



51-19 

 15-80 

 3-08 

 11-20 

 5-63 

 9-58 

 2-09 

 0-60 

 0-30 



0-40 

 0-008 



O-005 

 trace, 

 trace. 



trace, 

 trace. 



i)9-S83 



Denierara 

 River. 



3-01 



54-21 

 13-25 

 4-26 

 10-00 

 5 03 

 8-99 

 1-79 

 0-74 



0-04 

 1-49 

 0-013 



0-005 

 trace. 

 0-21 



trace. 

 100-()2S 



0/irine- 

 diahase. 



Ouyuni 

 River. 



3-00 



52-18 

 15-59 

 0-75 

 8-11 

 7-89 

 10-40 

 2-88 

 1-25 

 0-73 



0-16 

 0-G5 

 0-003 

 0-008 



0-16 

 ('-14 

 0-05 



100-351 



