722 MINER A LOGICAL DESCRIPTION OF THE ISLAND OF BANKA. 
of composition, profusely spread over an extentive surface. They 
indicate that the miners have met with large veins of this stone in 
their works in a situation intermediate between the primitive parts 
of mountain Bettung and the low track which follows on the west. 
From the traces I noticed on the remaining* strata the ore had been 
disposed superficially, and the Breccias have likewise been taken up 
near the surface. The fragments were highly diversified, and dif¬ 
ferent in form and composition from the Breccias I had hitherto 
found; exterior poitions were generally in a state of partial decom¬ 
position, but in many cases the ore of tin was still abundantly ad¬ 
hering. 
The fragments consisted of siliceous stone or of particles of de¬ 
composed granite of various sixes united by a cement of the com¬ 
mon Red-Iron-stone of the island. The substances observed on the 
surface are: 
1. Particles of quartz of considerable size of the constitution of 
the crystallized rock abovementioned frequently occurring at the 
mines in the neighbourhood (for instance at Robo-kli, Marawang, 
See. 
2. Minute particles of quartz more pure and regularly crystal¬ 
lized. 
3. Particles of felspar of considerable variety of colour and fi¬ 
gure : many of them having a blackish hue. 
The surface is very irregular and the fracture presents the sub¬ 
stances observed on the surface with many intervening cellulosities, 
filled with an earthy ochreous substance : some fragments, however 
were more compact and consisted of more minute particles of quartz. 
The irregularity of the form, the grossness of the component parti¬ 
cles, in comparison with those I had hitherto found, the numerous 
cellulosities which intervened and the ochreous crust with the com¬ 
pact portions of the Red-Iron-stone, retaining a deep red colour,: 
gave a peculiar characteristic appearance to the Breccias of Tshen- 
After leaving the neighbourhood of these mines I crossed the ri¬ 
ver of Kfindis near its source and entered the large alluvial track 
abovementioned which transmits the river of Maraw&ng and its 
branches. Several slight elevations are observed at a distance and 
the road is alternately rising and descending. From Tshengal large 
rocks of sand-stone are plentifully dispersed through the country, 
they are externally of a greyish colour ami marked by numerous 
