136 PROCEEDINGS OP THE ROYAL SOCIETY OF QUEENSLAND, 



The second type of Grey Phase is not nearly so con- 

 spicuous as the first, but is probably present in greater 

 amount, occupying as it does a considerable portion of the 

 western and north-western portions of the Enoggera area. 

 This type is finer grained, of a grey colour, has considerably 

 more biotite present (usually in small cr3^stals), and often 

 lias present quartz and felspar inter grown to give a rudi- 

 mentary granophyric structure. The plagioclases are again 

 andesines, and pyrites is always present. This type is some- 

 times found as inclusions in the Pink Phase and occurs as 

 small zenoliths in the Enoggera ( ?) Hybrid. {See 

 ]Microphotograph Plate III. No. 8.) 



(G. 44) 416. — Specimen from Portion 374, parish of 

 Enoggera. 



This is representative of the hornblende rich type of 

 the Grey Phase. {See Microphotograph Plate II. No. 4, 

 and Analysis E4.) 



Megascopic. — This rock has a remarkable appearance 

 in the hand specimen. Numerous long slender crystals of 

 hornblende, ranging up to 8 mm. in length and averaging 

 about 4 mm. are set in a fine-grained light-coloured bas? 

 and give the rock a pseudoporphyritic character. Pyrites 

 is present in small amount. 



Microscopic. — Fine-grained holocrystalline for the 

 most part, but Math large crystals of hornblende. Quarts 

 is present but not very conspicuous, occurring as small 

 allotriomorphic crystals and irregular patches. The 

 felspars are for the most part clouded with decomposition 

 products, but seem to consist for the inost part of 

 plagioclases. Some of the altered felspathic material shows 

 a tendency for vague intergrowth with the quartz, and this 

 is presumably Orthoclase. The plagioclases still show 

 indistinctly traces of Albite twinning, very few of them 

 being determinate. Those sections capable of determination 

 by the Michel-Levy method show a variation from inter- 

 mediate to basic andesines. Hornhlende occurs in 

 numerous elongated, relatively large crystals, which give 

 an apparently prophyritic character to the rock. This 

 impression is contradicted by two facts — first, there is no 

 sign that the hornblende is present in two generations; 

 and second, that the small plagioclases are idiomorphic to 



