190 ON THE GEOLOGY AND PETROGRAPHY OF BATHURST, N.S.W., 



vii. Igneous Division. 



a. Plutonic Acidic Rocks. 



1. Amphibole granite. — A crystalline, granular rock, composed 

 of quartz + orthoclase + plagioclase + hornblende.* This corre- 

 sponds to the granulite a amphibole of Fouque and Levy. These 

 authors, in the splendid work just referred to, define granulite as 

 consisting of black mica, oligoclase, orthoclase, quartz and horn- 

 blende. Granulite a amphibole merely differs from this rock in 

 the total or partial substitution of hornblende for black mica.f 



2. Granitite. — A crystalline, granular rock, consisting of 

 quartz + orthoclase + plagioclase -f magnesian mica. This agrees 

 with granitite of Fouque and Levy. 



3. Aplite. — A granular compound of potash felspar (orthoclase 

 or microcline) and quartz, with muscovite mica as an accessory. 



4. Graphic granite. — This variety of aplite, in which the quartz 

 laminae form figures bearing a fancied resemblance to Hebrew 

 letters, is sometimes found as water-worn fragments about Poor 

 Man's Hollow and at Perth. 



5. Greisen. — Thin veins of a rock, composed of quartz and mica, 

 may be found near the boundaries of the granite and slate country. 



6. Porphyritic granite. — In very many parts of the district the 

 felspar crystals of the granite are so large and well-developed, 

 being frequently two and three inches in length, as to entitle the 

 rock to be called porphyritic granite. 



7. Felsite. — An intimate, granular-crystalline admixture of 

 orthoclase and quartz. Common in the drifts. 



* Rosenbusch, Mikroskopische Physiographie der Massigen Gesteine, p. 

 29 ; Zweite Auflage. 



\ Mincnilogie Micro-graphique Roches Eruptives Francaises, pp. 156, 160. 



