716 GREAT SERPENTINE BELT OF NEW SOUTH WALES, Hi., 



arrangement (Plate xxix., Fig. 16). The garnets are often sur- 

 rounded by one or two thin shells of garnet, separated from the 

 mam crystals by prehnite, sometimes optically continuous with 

 that of the ground-mass. Finally may be noticed, a pink crystal- 

 line rock, studded with deep red garnets [M.B., 165]. This is a 

 most complex rock. It consists of beautifully zoned, red garnets, a 

 small amount of vesuvianite, with very anomalous, unusually high, 

 birefringence, and positive optical character (a rare feature) ; 

 a considerable amount of orthoclase, and also albite, some calcite, 

 and a brightly polarising ground-mass, part of which is wollaston- 

 ite, but which has undergone some alteration, and recrystallisation 

 that cannot be traced throughout in the single specimen available. 



If the determination of cassiterite in 164 be correct, it is evident 

 that these rocks must have been affected by highly active, pneuma- 

 tolytic solutions. 



(3) The Baldwin Agglomerates present an exaggeration of the 

 features of the Tamworth breccias. In the northern part of Hall's 

 Creek, near Bingara, where they become finer-grained, it is impos- 

 sible to distinguish them from the breccias, but, further south, the 

 size of the inclusions and their general characters become very 

 distinct. They were partially described by Messrs. David and Pitt- 

 man(3), who state that the matrix of the Cleary's Hill rock has 

 the appearance of the interstratified tuft's. It consists of much 

 fractured and corroded, macroscopic crystals of felspar and augite, 

 and calcite, with interstitial felsitic material, and here and there 

 small fragments of microcrystalline felsite, and larger, pebble-like 

 lumps of porphyritic andesite. The felspar is plagioclase, and, in 

 addition, quartz, ilmenite, pyrites, and epidote occur. In other 

 instances, much chlorite and prehnite are found. In this matrix, a 

 wide variety of pebbles is found. The following may be noticed : 

 granite and quartz-porphyry (rarely) ; keratophyres with pheno- 

 crystic albite and orthoclase(?), in a felsitic, sometimes spheru- 

 litic, base; black keratophyre with albite-orthoclase and augite- 

 crystals in a glassy, nuidal base, enclosing fragments of other 

 glassy keratophyres, rich in magnetite; trachytes; spilites, very 

 similar to those in the Eastern Series; trachy-andesites, with car- 



