680 GREAT SERPENTINE BELT OF NEW SOUTH WALES, iii., 



representative of the serpentine on Cope's Creek, five miles north 

 of Bowling Alley Point. On Chrome Hill, the eastern side of 

 the serpentine is highly schistose, streaked with grey and green 

 in an opaque white, talc-bearing, siliceous ground-mass, which 

 has thin films of limonite in all its shearing surfaces [N.T., 44]. 



We see, therefore, that, here, change to normal serpentine may 

 be followed by a further change to antigorite, or by carbonation 

 and silicification, with introduction of metalliferous minerals. 

 The significance of these observations will be fully discussed in a 

 later communication. 



{b). The pyroxenites are those rocks in which pyroxene becomes 

 dominant over the olivine. They are not at all abundant. In 

 two localities only have they been found to any extent. At the 

 head of Hall's Creek, south of Bingara, they are most abundant. 

 They consist [M.B., 323] of olivine passing into serpentine with 

 the mesh-structure and talc ; enstatite, changing along the 

 cleavages and on the periphery to green and brown anthophyllite, 

 and white, colourless tremolite passing from the boundaries out, 

 parallel to the vertical axis of the crystals; and diallage inter- 

 laminated with the enstatite, and in separate grains which are 

 less altered. A little granophyric chromite is present also. 



The rock from the head of Yellow Rock Creek, south of Crow 

 Mountain [M.B., 197] is almost a pure enstatite-rock. It contains 

 very little diallage and olivine, and is decomposing directly into 

 talc, with here and there a little serpentine. 



(c). The amphibolites are even more rare. They occur at the 

 Paling Yard, north-east of Barraba, and form the country of the 

 peculiar orbicular chromite. The unaltered rock [M.B., 189] is 

 compact, green, rough to the touch, and exceedingly tough under 

 the hammer. It is composed entirely of nearly colourless, tremo- 

 litic hornblende, which is prismatic in habit, rarely reaching a 

 greater length than 1 mm., and often multiply twinned. Scattered 

 about interstitially is a very small amount of clinochlore with a 

 noticeable pleochroism, yellow-brown to pale green. The double 

 refraction is too strong to allow it to be pennine, which it 

 resembles in pleochroism. The chemical analysis of this rock is 

 fully confirmatory of the microscopical determination. The 



