HI INE ft A LO GjC A X. DESCRIPTION OF THE ISLAND OF BANKA. 721 
crystals were sparingly found but copiously pure transparent quartz 
in masses, and that some of the detached fragment of felspar had a 
blackish colour. The specimens of ore here collected display the 
various forms (or combinations) in which it is found in the strata. 
At these mines I terminated my mineralogical remarks in this 
part of B&nka: it remains for me to detail those I made in my track 
across the island, between Marawang and the mouth of the river of 
Kutto-waringin. 
After leaving the neighbourhood of the stockade and proceeding 
in a western direction, the usual appearances are presented. Where 
mines have been worked the substances on the surface are of a mix¬ 
ed nature, siliceous and Red-Iron-stone. Beyond the mines of 
Tshengal appearances in some measure different from the former 
are observed ; and the subsequent track through the body of the is¬ 
land confirms the indications which are exhibited at Tshengal: here 
is the boundary, in the west, of the strata containing ore of tin ; in 
that extensive track towards Kutto-waringin and (northward) to the 
foot of the mountain Harass no traces of this metal have hitherto 
been discovered. I have not been able to visit the mountain of Ha¬ 
rass the most elevated on the island, but its Investigation is an ob¬ 
ject of importance in elucidating the mineralogy of Banka. The 
more elevated parts are doubtless granite, but it will be interesting 
to examine its southern declivities, to determine the foundation of 
the accounts of the original inhabitants and of the Chinese, which 
state that they are devoid of strata containing Tin-ore : if this is 
found to be the case, they differ from the declivities of the moun¬ 
tain Manumbing (the next in point of elevation) and from those of 
all the other mountains and hills of the primitive class, which have 
been mentioned in the foregoing details, and inclining towards which 
the most productive mines have hitherto been found. 
The Harass forms a long extended ridge divided into two separ¬ 
ate mountains each of which has a peak of considerable elevation. 
The direction is, on the whole, west-north-west to east-south-east: 
a long extended lqw range runs off towards the south-east. Of its 
highest point of elevation I can only form a conjecture, according 
to which it is, (comparing it with the Manumbing) elevated 1500 
feet above the level of the ocean. 
The appearances presented by the remains of the mines of Tshen¬ 
gal are very singular ; the spots where they have been worked are 
covered with large unwieldly fragments of Breccia of great variety 
