120 E. 0. Teale: 



show a similar range and variety. One example has very minute- 

 pericline twinning, and may be anorthoelase. 



Iron oxides are a little more plentiful; sume occur as very minute 

 grains abundantly scattered tlirough the rock. Con-oded xenolitlis 

 of both fine grained igneous and altered sedimentary rocks are 

 moderately numerous. There is an occasional flake of muscovite, 

 and little chlorite but no calcitt? was observed. 



No. 93 may be portion of an agglomerate. It contains numerous 

 xenoliths, apparently all of igneous origin. One is an altered ande- 

 site, the others are red, fine grained felsitic rocks, stained with 

 hematite, and showing small, partly kaolinised felspar phenocrysts. 

 The rest of the rock is generally similar to the previous examples. 

 Some of the quartz is rounded, but only slightly embayed. 



No. 91 is a specimen from the Dominion! copper mine, now aban- 

 doned. It is similar in grain, but lighter in colour than the other 

 examples described, but on exposure suffers a superficial red dis- 

 colouration, which appears to be due to the presence of some car- 

 bonate of iron. Otherwise the minerals present are similar. A 

 little copper pyrites is present in the dump, but as the shaft is full 

 of water, nothing could be seen as to the occurrence of the copper. 



(^) iifi rtz-C erntoph !J re . — No. 68. — This I'ock is of medium grain, 

 porphyritic. but inclined to be granular in hand specimens, and 

 has a general grey colour. The analysis show a silica percentage of 

 72.41, very similar to that of the acid rocks generally of this dis- 

 trict, but in the alkalies there is a marked difference in that soda is 

 6.86 and potash only 0.13. 



It is very closely comparable with certain rocks, described from 

 Navigation Creek, Noyang, by Howitt (32), under the names of 

 quartz-mica-porphyrite and quartz-porphyrite. 



Reference to tlie table witli analysis will show the close resem- 

 blance. 



Professor Skeats, in reviewing the volcanic rocks of Victoria (28, 

 p. 187). quotes Hewitt's analyses and gives some additional re- 

 marks on these rocks, desci'ibing them as quartz-ceratophyres. Re- 

 ferring to one example, he says, " This rock shoAvs a microcrystal- 

 line granular ground mass of quartz and felspar, with minute 

 microliths of chlorite, replacing probably ampliibole. The por- 

 phyritic constituents are as follows: — 



Oligoclas... of an acid variety, showing both all>ite and carlsbad" 

 twinning. Quartz in corroded and fractured crystals and chlorite 

 pseudomorphs after magnesia-iron-mica." 



