BY THE REV. J. MILNE CURRAN. 187 



product. It is met with in the excavations at the water-works, 

 and also in a tunnel driven to test the wash in the Bald Hills. 

 Thin layers of this mineral may sometimes be noticed in dried-up 

 water-holes, near the decomposed basalts in the Bald Hills. Clayey 

 ironstones are also found as a cementing material, binding quartz 

 pebbles together, forming post-pliocene river drifts. Peculiar pea- 

 shaped concretions of ironstone are often met with in deposits 

 formed from decomposing basalts. 



20. Mispickel. — Arsenio-pyrites or mispickel is tolerably abun- 

 dant in the schistose and slate country along the southern granitic 

 boundary. It occurs both massive and crystallized. This mineral 

 was found in a well, associated with iron pyrites, on Mr. Butler's 

 selection near Green Swamp, on the Kelso-Hockley B-oad. 



21. Iron pyrites. — Is very plentiful in the slate country about 

 Bathurst. A very notable occurrence was discovered in a shaft 

 put down by Mr. J. Wilde on Butler's farm, to the south of Perth. 

 The crystals were mostly cubes, and formed the greater part of 

 the rock. Microscopic crystals of pyrites are very common in 

 some of the slates about Cow Flat. I have also noticed yellow 

 iron pyrites in micro-slices of granite from a railway cutting 

 beyond George's Plains ; also in slices of the same rock from the 

 base of Mount Pleasant. It can easily be recognised in microscopic 

 sections by reflected light, the bright yellow of the pyrites being 

 clearly seen. 



22. Magnetite. — This is only known as a microscopic constituent 

 of basalt. It will be referred to, in detail, in dealing with the 

 microscopic structure of the basalts. 



23-28. Copper Minerals. — It has been already remarked that 

 the metalliferous minerals are confined to the zone of contact 

 rocks. It is in these rocks that native copper, malachite, copper 

 pyrites, grey ore, and azurite have been discovered. I have found 

 native copper in hornfels rock at Duramana, on Kelly's farm. 

 Malachite occurs sparingly at Cow Flat, south of Bathurst. In 

 the specimens I examined it seemed to result from some alteration 

 of azurite or blue carbonate of copper. In keeping with this fact 



