420 SIINERAL0G1CAL DESCRIPTION OF THE ISLAND OF BANKA. 
tin-ore is disseminated. The nature of the blac1c-clay, which I have 
observed with but one or tw r o exceptions in every mine I visited, 
and which is, at it were obtruded into the more regular strata, as 
an irregular coaguhmi, essentially different from the superficial ve¬ 
getable mould or from the other masses of pure clay which abound, 
deserves to be more accurately investigated and explained. 
In the Northern division of the Island of Banka the hills are 
divided into two separate ranges, one near the western the other in¬ 
clining towards the eastern boundary, between which an extensive 
space remains which is occupied by the Bay of Klabbet. 
This bay has, upon the wdiole, the same direction as the general 
range of hills, from north-west (or N. N. W.) to south-east (or S. 
S. E.) it is terminated in the south by the mountain of Harass : in 
the geographical account, the northern part of the island has been 
divided into two peninsulas according to the division naturally form¬ 
ed by this bay. 
The mineralogical appearances in the western range and its en¬ 
virons having been described, I proceed to the detail of those in the 
eastern. The rocks which project beyond the surface at the shores 
of the bay, as well as those dispersed through the entire western 
portion are granite: 1 examined them in my course through the bay 
at numerous points. The constitution of the islands of Pulo-Kkippa 
near the points Tunjong-Ru and Tanjong Mantung, which separate 
the outer from the inner bay, and which nearly meet each other 
from the west and from the east, is of the same kind : they are botli 
immense piles of granite rocks, similar to those above described, on 
which vegetation has commenced. 
The gradual inclination or meeting of the declivities of both ran¬ 
ges of hills towards the w r est from the eastern, and towards the cast 
from the western, is evident not only by the excavation which is fill¬ 
ed up by the bay but also by the course and discharge of the numer¬ 
ous rivers from both sides and which have been accurately enumer¬ 
ated in the geographical description of the island. 
I had an opportunity only of examining the eastern confines of the 
bay. Between the projecting points or promontories of the hills, 
