506 H. G. STTiith — Basic Intrusions, Radnorshire. 



present to say definitely whether the albite is magmatic in origin or 

 is the result of weathering. 



This rock presents some points of resemblance to the Skomerite 

 and Marloesite of Dr. Thomas/ but the evidence available suggests 

 that it is newer than the Lower Arenig, to which the Skomer 

 Volcanic Series is assigned. 



ANALYSES BY J. H. WILLIAMS. 



1. Olivine Basalt. 



Si02 



TiOa 



AI2O3 



FeaOs 



FeO 



MnO 



(Ni Co) 



BaO 



SrO 



CaO 



MgO 



K2O 



NagO 



LiaO 



Ha at 105° C 



Ha above 105' 



P2O5 



SO3 



CO2 



F . 



CI . 



Total 

 2. Diabase 



SiOa 



TiOa 



AlaOg 



FeaOs 



FeO 



MnO 



(NiCo)O 



BaO 



SrO 



CaO 



MgO 



K2O 



NaaO 



LiaO 



H2O below 100° C. 



H2O above 100° C. 



P2O5 



SO3 



CD2 



F . 



CI . 



48-66 

 2-23 



15-76 

 2-66 

 8-16 

 0-14 

 0-03 

 none 

 0-16 



10-90 

 5-68 

 0-05 

 1-25 

 none 

 0-70 

 3-04 

 0-22 

 0-43 

 0-20 



traces ? 



traces 



Total . . .100^25 

 Q.J.G.S., vol. Ixvii, pp. 196-201, 1911. 



