BY THE REV. J. MILNE CURRAN. 185 



abundance in this relation can be ascertained by treating a rock- 

 slice with acid so as to separate the soluble olivine and magnetite. 



10. Hornblende. — Is found as a macroscopic mineral in the 

 granite ; crystals vary in size, the largest I have noticed measuring 

 from one-sixteenth to one-eighth of an inch along the vertical axis. 



11. Actinolite. — Found to the south of Bathurst, forming veins 

 in quartz. Most of my specimens come from Cow Flat. It formed 

 fibrous, radiated masses of dark green colour, easily fusible before 

 the blow-pipe. After fusion it becomes strongly magnetic. Specific 

 gravity 3 -5. 



12. Muscovite. — Muscovite, or common mica, is found as an 

 accessory mineral in the Bathurst granites. Towards the edges of 

 the granite mass it often entirely replaces the black mica so 

 characteristic of the typical Bathurst granite. Muscovite occurs 

 in considerable quantities in the river sands. When fresh it is 

 usually colourless, when slightly decomposed it appears as a rich 

 yellow, and an opaque golden hue is very common. It also is 

 found in the sands of almost every creek in the district. 



13. Biotite. — Black, magnesia, iron mica occurs as small, partly 

 formed crystals and scales, disseminated through the granite, but 

 occasionally, particularly near the edges of the granite rocks, large 

 plates can be detected. By transmitted light it sometimes appears 

 of a deep green colour. After long heating it decomposes in 

 sulphuric acid. Fusible without much difficulty. Plates, corre- 

 sponding to basal sections, are easily picked out in decomposing 

 granites. The dark colour of the granite is due to the exceedingly 

 large proportion it contains of biotite and hornblende. 



14. Kaolin. — Kaolin, of various degrees of purity, can be found 

 both as decomposed granite in situ, and in small beds of trans- 

 ported material. A pure white kaolin was found on the Bald 

 Hills, a little to the right of the line of section A B marked on 

 the map. When washed free from particles of quartz it formed a 

 tolerably pure kaolin, but the percentage of iron was too high for 

 a marketable article. 



