372 GREAT SEKPENTIXE BELT OF NEW SOUTH WALES, vii., 



small plieiiociysts of albite in a base of not very tine grainsize. 

 This is spongy in texture, consisting- of laths of albite, with a small 

 amount of magnetite-dust; rather larger, well formed laths lie in 

 the mass of microlites, together with large grains of quartz often 

 with chalcedonic margins. Exactl}' similar rocks have been 

 described from Pipeclay Creek, a mile and a half further to tlie 

 south-east along the same band of rock(5, pp. 155-(3). Another 

 type of quartz-keratophyre occurs in the creek in the Water 

 Iveserxe between Portions ol and o3. This is exemplitied by 

 specimens Nos. 1388 and 1421. The former contains quartz, form- 

 ing a general groundmass, in which are laths of albite with a 

 general trachytic aTrangement, .sometimes less abundant than the 

 quartz, but generally more so. Scattered about is chlorite (rei)lae- 

 ing augite), and crystals of magnetite. J^inesof shearing traverse 

 the rock, and the magnetite is often congregated in these. 



As a final example of siliceous keratojjliyres, we may instance 

 Xo. 1401, from the extreme southern end of the eastern mass of 

 keratophyre. This is a very fine-grained rock, crushed slightly 

 and intersected by veins of quartz, often very narrow. The ground- 

 mass consists of irregular patches of minutely granular, untwinned 

 grains of felspar, in wliicli are embedded innumerable minute laths 

 of acid plagioclase with a more or less trachytic arrangement; 

 between these is a small amount of Hnely divided magnetite-dust, 

 and small irregular grains of quartz occur among this. There are 

 phenocrysts of albite, and a few irregular patches of chlorite. The 

 magnetite also occurs in the lines of crushing, being evidently 

 introduced secondarily. 



The mafjnetife-l-eralophi/res may be subdivided into those whicli 

 contain quartz, and those which do not. We will consider the latter 

 first. Near the head of Bog Hole Creek, in the south-eastern end 

 of Portion 37, is a small mass of htematitic iron-ore, and by it is a 

 very liaematitic keratophyre (No. 1427), which consists of fine- 

 grahied, tracliytic albite-latlis, witli small phenocryst-laths 0-5 mm. 

 in length, densely impregnated with more or less oxidised mag- 

 netite. The rocks contain angular patches of trachytic kerato- 

 phyre, almost free from iron-ore. The latter is aggregated in the 



