GEOLOGY OF THE GLOUCESTER DISTRICT, N.S.VV. 



255 



ritic, displaying an abundance of small red phenocrysts of 

 felspar, with a variable number of small quartz phenocrysts. 

 Under the microscope the groundmass varies from crypto- 

 crystalline to glassy, spherulitic structure is commonly 

 present. The quartz phenocrysts are strongly corroded 

 as also are the felspars. Most of the felspar phenocrysts 

 are albite, but some orthoclase phenocrysts also occur. 

 The only ferro-magnesian mineral found is an occasional 

 small phenocryst of a pale green hornblende. 

 Chemical Composition. 



SiO a 



74-56 



A1 3 3 



12-87 



Fe 2 3 



1-80 



FeO 



0-36 



MgO 



0-29 



CaO 



0-28 



Na 2 



4-91 



K 2 



3-43 



H 3 O(100°C.) 



0-35 



H 2 (100° C.) + 



■ 0-91 



C0 3 



0-01 



Ti0 3 



0-40 



Zr0 3 



absent 



P 2 5 



0-04 



Norm. 





Quartz 



32-16 



Orthoclase ... 



20-02 



Albite 



41-39 



Anorthite 



1-39 



Corundum 



0-61 



Hypersthene... 



0-70 



Ilmenite 



0-76 



Hematite 



1-76 



so 3 



absent 



01 



trace* 



S(FeSr) 



absent 



Cr 2 3 



absent 



NiO and OoO 



absent 



MnO 



0-03 



BaO 



004 



SrO 



trace* 



Li0 2 



absent 



v 2 o 5 



absent 



Total ... 



100-28 



Specific gravity 2-622 



Classification. 

 Class I. Persalane. 

 Order 4 Britannare 

 Rang 1 Liparose 

 Sub-rang 4 Kallerudose 

 Magmatic name Kallerudose 



It will be seen that this rock is not very different from 

 the No. 1 Flow, differing mainly in containing a larger pro- 



