1867.] 



TIMINS — MALVEEN HILLS. 



363 



rock was nearly that of a trisilicate, becoming in places more basic. 

 In the more crystallized portions there was some brilliant black 

 mica, which I found by analysis to be lepidomelane. 



yill. Felsjpathico-Hornhlendic Rocks. 



These rocks, in which hornblende predominates, have been de- 

 scribed by Professor Phillips* as " mottled syenite," and by Dr. 

 Hollf as '' diorite." They occur in all the hills, excepting the 

 Eagged Stone. Their origin is probably similar to that of the bedded 

 traps, lavas, and volcanic ash-beds south and south-west of the 

 chain ; and, like them, they appear to be partly intrusive and partly 

 sedimentary ; but being of much earlier age, and having undergone 

 more extensive metamorphosis, resulting in a more complete crystal- 

 lization, their mineralogical character is different. They are often 

 distinctly stratified ; granular beds alternate with others of larger 

 crystalline structure; the ^' diorite " passes, abruptly or gradually, 

 into a subcrystaUine rock ; and lines, marking the bedding, may be 

 traced continuously from one to the other. The hornblende and 

 felspar are sometimes extensively segregated, and in other places 

 they form a confused aggregation of indistinct crystals. Quartz is 

 an occasional constituent. They are associated with other rocks, of 

 metamorphic character, in connexion with which they vdll have to 

 be further considered. 



The following analyses show the composition of these rocks, and 

 its resemblance to that of the trap-dykes and lava-beds throughout 

 the chain : — 





1 

 w. 



< 



O M 



5a 



51 



6 



a 



h5 



c3 







LVII. 



LYIII. 



LIX. 



LX. 



LXI. 



44-22 



45-67 

 56-61 

 44-76 

 46-10 



20-66 

 20-17 

 21-72 

 16-60 

 22-67 



10-80 



11-28 



5-26 



8-43 



6-36 



Trace. 



Trace. 



11-32 



10-86 



4-74 



9-92 



13-63 



717 

 5-43 

 3-63 



8-56 

 6-59 



1-80 

 1-55 

 1-55 

 2-68 

 2-07 



4-03 

 5-04 

 6-34 



8-85 

 1-88 





015 

 0-20 





0-70 





LYII. Fine-grained bed in diorite, on the east slope of the North 

 Hill. Small crystals of hornblende, white uncrystallized felspar 

 disseminated, and a little pyrites. G=2-990. 



LYIII. Another bed interstratified with the last-mentioned, more 

 largely crystallized. Hornblende and white felspar. 



LIX. Diorite, south of the large quarry at North Malvern, re- 

 sembling, in its external characters, the Labrador hornblende -rock 

 found about fifty miles north of Cuff Harbour. Black hornblende, 

 quartz, and pink and pinkish white felspar, of which the cleavage 

 resembles orthoclase, but the chemical constitution is more nearly 

 that of andesine. G =2-894. About three-fourths of the portion 

 analyzed consisted of felspar. 



* Op. cit. p. 41. * t Op. cit. p. 83. 



VOL. XXIII. PART I. 2 C 



