204 
and a good deal of earthy hematite. No groundmass and no 
felspar or sericite. Structure roughly foliated. There has 
been a very considerable amount of crush, resulting in deve- 
lopment of undulose extinction and granulation of quartz. 
In addition to liquid and gas cavities, the quartz contains 
numerous round flakes of biotite and muscovite, and small 
crystals of magnetite. Large flakes of muscovite, often bent 
and broken, are scattered through the rock, with a general 
parallel arrangement. Pyrite in fresh-looking cubes. A little 
rutile and zircon present in crystals and fragments. 
xxiv. Mount Barker, outcrop about 300 yards 
west of the scarp of the mount. 
Macroscopic characters —Rather thin bedded 
rock, somewhat coarser than xxiii, and not so hard or 
vitreous. More yellowish in colour. 
Microscopic character s.—Texture coarse, 
An aggregate of irregular quartz grains in optical contact, 
with no interstitial cement at all. Quartz is clear and glassy, 
and singularly free from liquid and gas cavities, except 
such as lie along secondary solution planes. On the other 
hand, little round flakes of biotite are extremely numerous. 
These are exactly like those so characteristic of gneisses, 
and indicate that the material was derived from a gneiss, and 
not from a granite. A very occasional grain of orthoclase is 
present, but no other felspar. 
xxv. Blakiston, two miles west of Mount Barker. 
Macroscopic eharacter s.—Thin bedded schis: 
tose quartzite, whitish-grey in colour, moderately fine grain, 
fractures across the grains, somewhat micaceous. 
Microscopic character s—Very similar to 
xxiii., but very much more schistose. Biotite enclosures in 
quartz like those in xxiv., together with some andalusite. 
Parallel lines of inclusions (liquid and gas) run indifferently 
through all the grains. A fair amount of broken and bent 
muscovite flakes and brown-green grains and fragments and 
prisms of tourmaline are present. 
RXV Кт р вот Буй пу Ооа ny, 
Macroscopie characters.—Very white, hard 
quartzite of fine grain. Contains no recognisable constitu- 
ents other than quartz. Fractures across the grains. 
И созоор le. cámara ab ens lo all mespects 
similar to xxiii., except that texture is more uneven. Largeish 
quartz fragments are set in a finer-grained mass of the same 
material. A fair amount of muscovite is present. Structure 
very markedly schistose. 
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