BY W. G. WOOLNOUGH. 



797 



Analysis by G. J. Burrows. 

 Per cent. 



SiO., 59-94 



AI2O3 ... 15-61 



Fe^Oa 1-55 



FeO 6-25 



MgO 2-53 



CaO 6-65 



Na20 2-88 



K2O 2-06 



H2O+ 0-57 



H2O- 0-39 



TiO.^ 1-08 



P.2O5 0-64 



Total 100-15 



Per cent. 



Norm. Quartz 15-78 



Orthoclase 12-23 



Albite 24-63 



Anorthite 23-35 



Diopside 5-35 



Hypersthene 11-93 



Magnetite 2*32 



Apatite 1-34 



Ilmenite 2-13 



Total 99-06 



Molecular proportion* 

 994 

 153 



10 



87 



63 

 119 



47 



22 



32 



22 



14 

 4 



Sub-Rang 

 Bandose. 



Dacite: near southern boundary of Portion 113, Parish 

 Marulan. (Plate Ixix., fig.3.) 



The rock is porphyritic, with a finely crystalline base. Pheno- 

 crysts up to about 10 mm. diameter constitute about 40 percent, 

 of the material. Body-colour greenish grey. The most con- 

 spicuous minerals are large glassy quartz-grains, slightly opaline 

 in places, rather scarce; greenish- white, dull grains of felspar; 

 and aggregates of dark ferromagnesian mineral. 



Microscopic characters : holocrystalline porphyritic, ground- 

 mass panidiomorphic-granular, with average grain-size of about 



