208 PROCEEDINGS OF THE ROYAL SOCIETY OP QUEENSLAND, 



Description of Plate V. 



Plate V. shows four photographs of hand specimens of the 

 Montville rhyohte. The first three are mangified X 2 and the 

 fourth X i§. 



Fig. 1. — Rhyolite from the Narrows, Obi Obi Creek, showing the litho- 

 physae with their hollow rounded form and concentric 

 coats. Magnified X 2. 



Fig. 2. — Rhyolite from Bon Accord Falls. It shows the spherulites light 

 in colour in a cryptocrystalline groundmass. Phenocrysts 

 of pink orthoclase occur through the rock sometimes as a 

 nucleus to the spherulite. Magnified X 2. 



Fig. 3. — Rhyolite from The Narrows, Obi Obi Creek, showing very well 

 the spherulitic structure and containing much more 

 " secondary " quartz than most of the rhyolites. Magnified 

 X 2. 



Fig. 4. — Rhyolite from Bon Accord Falls, showing the fluxion structure. 

 Magnified X \%. 



