714 MIN ERA LOGICAL DESCRIPTION OF THE ISLAND OF BANKA. 
remarkably white and possessed in a great degree the character of 
pure clay: in some of the masses minute crystals of quartz were im¬ 
bedded. The external appearance and fracture of the granite rocks 
near Robo-klf is similar to those found near the foot of the moun¬ 
tain abovementioned, the felspar is irregularly distributed and gives 
it often a marbled appearance. The specimens I collected from the 
aqueducts of the different mines of this district were highly diversi¬ 
fied, embracing, with the exception of slate, almost every variety 
hitherto enumerated, as remaining after the process of the washing 
of the ore. Having passed the environs of these mines, rock-crys¬ 
tals are no longer observed among the stones remaining on the sur¬ 
face or at the canals. The first mines which I examined after en¬ 
tering the district of Marawang are indicated by these substances to 
be situated in a continuation of the strata above mentioned. This 
is the case with the mine of Kimsowd, the largest of the district 
which has been attempted again after a former failure. 
In a direction nearly west, about one mile from the stockade, I ex¬ 
amined a mine which is of a different nature. In ail those I had hi* 
therto visited the strata were composed of substances derived from 
the primitive parts of the island, and the Red-Iron-stone or Breccias 
formed comparatively only a small proportion. 
This mine existed in a tract composed almost entirely of layers of 
Red-Iron-stone and the siliceous particles were sparingly distribut¬ 
ed. As it was a small mine, and had long been worked, a very ex¬ 
tensive plain was opened and exposed to view, intersected by nume¬ 
rous parallel canals, remaining from the successive works of the 
miners, as the strata were exhausted ; these, with the substances 
disposed over the surface and the sections of the hill, afforded an in- 
strutive view of its constitution. 
The substances covering the plain just mentioned were of differ¬ 
ent kinds; some were fiat or tabular with the sides uneven and cor¬ 
roded, the surface covered with a yellow ochre and the fracture dark 
coloured : some again were irregular, massive, more uneven or groov¬ 
ed on the surface, the fracture shewing a disposition to the forma¬ 
tion of nodules (geodes) while the interstices were filled up with an 
earthy substance; others consisted of minute particles of silex, bed¬ 
ded in reddish ochre possessing different degrees of hardness and 
adhesion forming a friable Breccia. A few only exhibited a close 
fracture, resembling the Red-stones of Belinyu. Upon the whole 
considerable diversity occurred in the substances found at this mine, 
