138 PROCEEDINGS OF THE ROYAL SOCIETY OF QUEENSLAND. 



edge of this is optically discontinuous with the remainder, 

 and is evidently a "reaction rirn." The crystal proper 

 shows both Carlsbad and Albite twinning and is con- 

 siderably larger and quite diflt'erent in appearance from the 

 plagioelases of the enclosing rock. It is evidently a 

 xenoeryst. Unfortunately the section is in such a direc- 

 tion that the plagioclase is indeterminate. Hornblende 

 occurs as numerous acicular crystals showing marked 

 pleochroism and in some stouter crystals, these latter show- 

 ing intergrowths with biotite. Biotite is present in small 

 amount, generally in irregular patches associated with the 

 hornblende. Pyrites occurs as numerous small crystals 

 scattered throughout the slide. Apatite is present as 

 abundant minute crystals. 



Order of consolidation. — Normal. 



Name. — Hornblende Microgranodiorite. 



(G. li) 418. — Specimen from western part of area. 



This is representative of the second or biotitic type of 

 the Grey Phase. 



Megascopic. — A grey tine-grained holocrystalline rock 

 composed of occasional phenoerysts of quartz and white 

 felspar set in a grey even-grained ground mass. Some 

 small veins of pyrites are apparent. 



Microscopic. — Only one undoubted phenoeryst (an 

 altered felspar) was seen in the slide examined, the rock 

 being made up of a fine-grained but somewhat variable 

 aggregate of cjuartz felspar hornblende and biotite. The 

 quartz occurs in very irregular crystals moulded about and 

 enclosing all the other minerals. Occasionally, however, 

 the quartz crystals have moulded about them a discon- 

 tinuous ring of small ferro-magnesian minerals. Ortho- 

 clasc is present as hypidiomorphic crystals which some- 

 times show simple Carlsbad twinning. Plagioelases are 

 numerous and seem to be divisible into two groups, the 

 first a medium oligoclase and the second an oligoclase- 

 andesine. A felspathic xenoeryst with similar outline and 

 reaction phenomena to that described above in No. 345 is 

 present in this slide. It shows no twinning, however, and 

 resembles anorthoclase in general appearance. Hornblende 

 occurs in comparatively large elongated green crystals which 



