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



formula, but a new analysis [N.T., 321] gives figures approximat- 

 ing to the chlorite-formula : 



5(MgFe)0, (AlFeCr) 2 3 , 3 Si0 2 , 4 H 2 0. 



The earlier analysis shows a great excess of alumina and 

 deficiency of magnesia, and this is doubtless due to the use of 

 only one or two precipitations of alumina with it. In the newer 

 analysis, the first alumina-precipitate was noticeably more bulky 

 than the second and third, and five reprecipitations, in all, were 

 employed. Mr. Mingaye, on my calling attention to the unsatis- 

 factory nature of the older analysis, made another, of a specimen 

 in the Mining Museum in Sydney, with the result tabulated. 

 This shows more alkalies and nickel, and less water than N.T., 

 321. The latter analysis was, therefore, checked and confirmed 

 in the figures for those oxides. A real variation does, therefore, 

 exist. 



Other occurrences of pseudophite are quite different from this. 

 Dr. Flett, in the Lizard (40), and Professor Lacroix, in the 

 Pyrenees(28), have both noted pseudophite occurring with peri- 

 dotite; but, in both cases, it replaced alkaline felspar, and showed 

 a pseudomorphous character, and want of homogeneity.* The 

 Hanging Rock specimen is absolutely homogeneous and structure- 

 less, and so finely divided it is with difficulty possible to make 

 out the individual chlorite flakes in the mutually compensating 

 mass. 



(6). The gabbroid rocks occur here and there, and in greater 

 or less amount, all along the serpentine-belt. In the localities 

 where they are but slightly developed, it is clear that they 

 intrude into the serpentine; but where they are most abundant, 

 as east of Cobbadah, their relationships are not so obvious. The 

 original rocks must have been fairly uniform in character They 

 were eucrites composed of pale green dial lage and bytownite, and 

 had an even, granitic texture, and medium grain-size. The ex- 

 ceptions to this were comparatively few, and comprise pegmatitic 

 eucrites and olivine-gabbro. 



* Mr. Howard Fox, who first noted this mineral at Kynance (Minera- 

 logical Magazine, 1891, p.275) thought it replaced plagioclase. That is 

 not possible at (jew Graze, but may be elsewhere in the Lizard. 



