400 MINER A LOGICAL DESCRIPTION OP THE ISLAND OF BANKA. 
solid parts, are extensive masses of Clay of various colours, from 
pure white to yellow and red: a black earthy substance which, for the 
sake of distinction, I have called Black-clay occurs in irregular 
masses or coagula (with few exceptions) in every mine; and the ter¬ 
mination of a stratum is indicated by a peculiar white clayey sub¬ 
stance which becomes friable by drying and is called Kongiay by the 
Chinese. 
I have proposed in the mineralogical remarks, to follow the or¬ 
der in which they were made during a tour through part of the Is¬ 
land of Banka, without any retrospect to regularity or relative im¬ 
portance ; dating the commencement of my investigations from my 
arrival at Kampak in March after a passage of two days from the 
settlement at Rangam. In my course around the western extre¬ 
mity of Bank&, during which the vessel remained near the shore, I 
had a good opportunity of observing the direction and extent of the 
mountain Manunibing and its western and eastern appendages, with 
part of that range which extends from it, to the eastward. 
That tract of country which lines the Bay of Jehus between the 
hills of Pari-pari on the north, and of Manumbing and its appenda¬ 
ges on the south, must be considered as one of the Alluvial districts 
of B&nka; besides several others of less note, the rivers of Sungei- 
bulo, Kampak, Palangas and Rambat pass through it. In procee¬ 
ding up the river of K&mpak I remarked numerous rocks projecting 
beyond the surface. 
I examined them at a cluster, which forms a small Island, called 
* 
by the natives Bdtu-lukut, about 100 y t ards in circumference. 
The external form of the entire rooks is rather rounded than sharp ; 
the highest project, at the present season, about 10 feet beyond the 
level of the river: The external colour of the separate rock is 
of a dirty hue ; the surface is very unequal and rough, exca¬ 
vated by fissures, crossing each other in various directions, into ir¬ 
regular angles and rhombs Stc. or marked, in a similar manner 
by white streaks or fines. The fracture is intensely white, some 
portions appearing glistening as pure quartz, others dull and dial- 
