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APPENDIX. 
A Short Description of Some op the Cape River Rocks Examined in Thin Sections 
UNDER THE MICROSCOPE. Bt WiLDIAM H. RanDS. 
1. A dark-colourod, fine-grainod hornhlcnde scJiist, from Union Reef, near Mount 
Davenport. lUe aJide consists almost entirely of green hornblende and quartz. Tlie qurrtz 
contains enclosures of apatite and other minute enclosures. In a section cut transversely to 
the cleavage the longer a.xos of the hornblende have a in ear arrangement. 
d. A viliite iiiiccc schistj from Mount Davenport. The slide consists cliielly of (^itartz in 
small grains, with mica. In a section cut transversely to the cleavage of the rock the mica is 
arranged in layers. 
_ 3. A Imrnhhnde schist, from the southern slope of Mount Davenport. Green hornblende, 
beautifully cleaved, with bands consisting of grains of qiMvtz. There is more hornblende 
than quartz in the section. Magnetite occurs in grains. 
4. A rod line-grained pruMife, from Mount Frank. Qtiartx occupies the larger portion 
of the slide ; it is full of minute enclosures. Plagioclase felspar, which is much kaolinizcd. 
White and black mica. The slide contains numerous large specks of magnetite. 
7. Felsite, from dyke in schists, Pentland Reefs. The rock consists of a fine decom- 
posed felspathie ground-mass, with throughout it. 
8. A red, medium-grained yra?is7e, from Homestead Range. The section is rather thick 
and indistinct. The slide contains crystals of plagioclase felspar, and also beautiful star-shape 
splierulites of plagioclase felspar; quartz, with enclosures of magnetite; mica; and specks of 
magnetite throughout the slide. 
12. Dolerile, from dyke near Specimen Creek, Mount Remarkable. This slide is very 
thick, and the only minerals thal can be determined are decomposed yefspur and small specks 
of augite in a semi-crystalline ground-mass. 
15. Oraphio granite, from dyke near Specimen Creek, Mount Remarkable. The slide 
consists of elongated plates of quartz in felspar. All the quartz extinguishes simultaneously ; 
and the same is the case with the felspar. 
16. Quartzite, from Golden Hill, near Mount Remarkable. This rock consists almost 
entirely of semi-rounded and irregular-shaped granules of quartz, containing numerous 
enclosures, among which are small acicular crystals, probable apatite. There are crystals of 
magnetite in the slide, and some ferrite. 
17. Quartz felsite, from a dyke on the ridge north of Mount Remarkable. The slide 
consists of an amorphous ground-mass, with blebs of quartz throughout it. It contains a little 
ferrite. 
22. Gahbro, a dark crystalline rock from a dyke near Specimen Creek. This slide is 
made up of diallage, which is very feebly dichroic, a plagioclase felspar, and mica. Small 
grains of magnetite occur throughout it. 
24. A wdiito kaolinizcd felsite, from Running Creek, Norwood. It consists of an 
amorphous ground-mass, with minute grains of quartz throughout it, which have a banded 
structure. There arc also small grains of magnetite, and a few porphyritie crystals of felspar. 
25. A reddish-brown felsite, from Running Creek, Norwood. The slide shows a line 
felspathie ground-mass, with minute lath-shaped crystals of felsjiar throughout it. Porphyritie 
crystals of plagioclase felspar, with enclosures of apatite and magnetite; a few porpihyritic 
crystals of orlhoclase felspar. Crystals of magnetite occur in the ground-mass. Ferrite occurs 
in considerable quantity, giving the red colour to the rock. The rock show's a beautiful perlitio 
structure. 
26. A purplish felsite or porphyry, from Running Creek, Norwood. The rock consists 
of a dark-colourod amorphous ground-mass, containing a large amount of ferrite, and showing 
in parts a well-marked fluxion-structure. There are numerous porphyritie crystals of 
decomposod/tViipu/-, most of which w'ere rubbed away in the preparation of the slide. Large 
crystals of magnetite occur. 
27. Dolerite, from a dyke in Chinaman’s Gully, Sandy Creek. A dark, fine-grained 
rock with a spherulitic structure on w'cathering. A felspathie ground-mass full of small 
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