1200 
Very schistose hornfels in the same island the layers of which 
dip away beneath the rocks mentioned above consist almost 
entirely of feldspathised schists with intercalated layers of granitic 
material which are very thin and partly can only be observed 
under the microscope. In this hornfels too, larger feldspars contrast 
with the fine crystalline quartz-biotite-mixture surrounding the feld- 
spars. Here also, inclusions of quartz and biotite occur in small 
number in some feldspars, sometimes being arranged in the direction 
of schistosity. Exceptionally and in a small number, these inclusions 
also occur in a hornfels near the contact with the granites in the 
little island I, and here too a more or less distinct arrangement parallel 
to the schistplanes of the rock can be observed ; however, for far 
the greater part the feldspars are totally free from inclusions. More- 
over, this rock is much coarser crystalline than those mentioned 
above. Some larger feldsparerystals occur in the finer crystalline 
mixture. The structure of the hornfels is very much like that of 
the adjoining granite rocks and no sharp line of demarcation exists 
between the two kinds of rocks. 
Further away from the contact, metamorphic rocks were collected 
in which much muscovite is present along with biotite. 
In the southern part of the island II, similar granitic rocks as in 
the northern part of the island I occur; here the feldspars are very 
strongly. sericitized and the rock contains much secondary calcite ; 
numerous pyritecrystals also occur. Adjoining these granites, but 
dipping away from the granite with strike W. 20 N. and dip 40° 
N,E. dense cherts and sericite-schists occur, which on microscopical 
examination prove to consist of a very fine-grained mixture of quartz- 
crystals and aggregates of small quartz-grains. In the quartz-mixture 
sericite occurs in varying quantity; along with sericite, chlorite, 
iron-ore and some apatite occur. These rocks show no traces of 
contactmeta morphism. 
Rather well crystallized muscovite schists in the banks-of the 
St Pakis have been mentioned above. 
Not far downstream from the kampong Pakis rocks resembling 
hornfels are found, in which much muscovite occurs along with 
biotite; in some of them traces of feldspathisation were observed. 
However, many of the rocks examined are free from feldspar; they 
contain a few larger quartz crystals, with undular, extincuon, or 
aggregates of quartz-grains in a finer-crystalline mass chiefly, con- 
sisting of quartz with biotite and muscovite. 
Tourmaline crystals of idiomorphie or almost idiomorphie limitation 
are sometimes rather numerous, a blue core is sometimes rather 
