NOTES ON SAMPLES OF RUCKS. 373 
42. These are other instances of the formation of schistose 
rock composed almost wholly of foliations of quartz grains in 
some parts of very small size and characteristically drawn out. 
In parts small “eyes” of felspar are observable, usually sur- 
rounded by narrow foliations of alkali mica. 
45. The contact of aplite and quartz schist is shown in one 
sample. The former is of the character already spoken of, ortho- 
clase, microcline, and microperthite set in a mass of broken up 
quartz and felspar, with a little muscovite and biotite. 
The quartzite schist is very fine-grained, the quartz-grains being, 
as elsewhere, drawn out so as to be longer than broad. Here and 
there are grains of orthoclase. Scattered through this, and also 
separating the lines of quartz grains and thus producing a schistose 
structure, are numerous flakes of mica, mostly biotite. 
This is one of those very quartzose fine-grained schists which I 
have observed to occur near the contacts of great plutonic masses 
and sedimentary rocks into which the former have intruded. I 
have observed and described* such a case between the Limestone 
River and Marengo Creek. 
33. An extreme form of metamorphism appears to be when the 
aplite has been completely crushed and comminuted and then 
regenerated into a fine-grained micaceous schist, but with traces 
here and there of orthoclase crystals and with secondary quartz. 
The rock has in such cases been so completely altered by meta- 
morphism that it is only by the traces of felspar that it can be 
distinguished from a fine-grained mica-schist produced from a 
sedimentary rock. 
(3) Quartz Hornblende ee ite. 
28. This slice shows large broken and wasted crystals of hone 
blende of a yellowish- -brown colour and with the ends in tints of 
blue. It is not strongly pleochroic in shades of dull green and 
yellow. I found the obscurations in two crystals to be 10° 42’ 
and 17° 56’ respectively. Biotite also occurs in smaller amount, 
and is somewhat bleached with elimination of magnetite. 
The plagioclastic felspars are so much altered that no reliable 
obscurations could be obtained, but so far as they gave any results 
they suggested Labradorite. A smaller generation ‘of these felspars 
is included in the hornblende. 
48. In another sample the felspars were numerous and more or 
less ideomorphic but much converted into mica. The only obscur- 
ation angles obtainable were 22° 22’ and 21° 20’ on either side of 
the twin plane in the zone P.K., indicating Labradorite. Horn- 
blende in this slice is plentiful but considerably broken and wasted. 
The obscuration in a section near to M., I found to be 16° 30’. 
* Notes on the Rocks occurring between Limestone River and Mount Leinster. Reports 
of the Mining Department, Victoria, September, 1890. 
