492 H. S. JEVONS, H. I. JENSEN, T. G. TAYLOR AND C. A. SUSSMILCH. 



Series III. Specimens from Various Parts of the Mass. 



Six specimens taken from exposures on various parts of 

 the mass other than the two principal quarries have been 

 examined in detail, and they prove that both the pallio- 

 essexite and the various types of the main mass of essexite 

 present everywhere the same features as those specimens 

 from the quarries already described. The following points 

 of difference are perhaps worth noting, though none of 

 them appear to be of great importance. 



Specimen Y. A paliio-essexite from Cactus Hill, north 

 of Emu Quarry, is very similar to specimen B, but poorer 

 in biotite, and a little richer in apatite. 



Specimen X. From the middle of the stone wall, south 

 of Greystanes. Differs from S (rather O, J, P) in that (1) 

 the augite is more titaniferous, having occasionally quite 

 a copper colour, and is the most abundant constituent; (2) 

 ilmenite occurs in large hexagonal tables, with much leu- 

 coxene; (3) apatite in long acicular crystals probably forms 

 5% of the rock; (4) the felspar so far as preserved is plagio- 

 clase, from labradorite to oligoclase, mainly the latter, but 

 large interstitial patches of analcite occur in the rock. 

 Another specimen of the same variety from the north end 

 of the stone wall is coarser, and has augite crystals 10 mm. 

 long. 



10. Characters of the Original Minerals. 



The foregoing detailed descriptions are intended to give 

 precise ideas of the varieties of the rock found in different 

 parts of the mass. The features of interest in the minerals 

 composing the rock require separate treatment, the 

 characters of the felspars and of their decomposition pro- 

 ducts, being especially noteworthy. The original minerals 

 will be treated in this section, and those of secondary 

 formation in the next. 



