532 THE GEOLOGY OF NEWBRIDGE, NEAR BATHURST, N.S.W., 



quartz and felspar, fine-grained, also a little muscovite; and there 

 are large patches of intergrowth with a net-like structure of 

 quartz and orthoclase, rarely pseudospherulitic, but frequently- 

 arranged perpendicular to the sides of a square, that is divided 

 into four diagonally. Fig. 3 is a sketch of such an intergrowth. 

 This appears due co the Baveno twinning of the felspar crystals, 

 with which the quartz is intergrown, as suggested to me by Dr. 

 Woolnough. Other examples occur in which the quartz crystals- 

 are arranged like the barbs of a feather. This is perhaps referable 

 to Carlsbad twinning of the enclosing felspar. 



The most remarkable of the granophyres that I have seen in 

 this district is that which occurs in a vein 30 feet wide, crossing 

 the railway line at the 162|-mile peg. Macroscopically it is a 

 hard, white, apparently felsitic rock, with thin flakes of biotite. 

 Microscopically (see Plate xxiii., fig.2) it is almost entirely ortho- 

 clase, containing every variety of graphic intergrowth of quartz, 

 from the development of very small pear-shaped quartz grains 

 forming long strings, up to large iishhook-like patches of quartz 

 imbedded in orthoclase. Quartz also occurs in phenocrysts. 

 There is a little muscovite in square flakes, and long pleochroic 

 strips of biotite. 



It is believed that this is the first record of granophyre from 

 the neighbourhood of Bathurst. 



(c) Ajylitic Veins. — Aplitic veins are fairly common, both in the 

 granites of the massif and intruding the surrounding slates. In 

 the slate near the George's Plains Creek (Railway Reserve near 

 Portion 65, Galbraith) there is a vein of pink aplite containing 

 quartz and felspar, with but few grains of biotite. It is fine-grained 

 (1mm.). It cuts through an older vein of the same mineral com- 

 position, but of much coarser grain (5 to 10 mm.). The felspar 

 seems to be mostly orthoclase. This association of a fine-grained 

 aplite vein cutting a coarse-grained aplite vein also occurs on the 

 Wimburndale Creek, at the point where the Peel Road crosses 

 it, some nine miles north of Bathurst. The finer-grained rock 

 there is almost identical with the Newbridge aplite above. It is 

 composed of predominant orthoclase, with oligoclase and micro- 



