MIN ERALOGICAL DESCRIPTION OF THE ISLAND OF BANKA. 719 
1. The siliceous stone consisting 1 of regular crystals, mentioned 
in the description of the mines of Sungie-liat (on the road to Robo) 
of Robo-klr &c., possessing often a disposition to separate into 
rhombs, pyramids or parrallellograms. 
2. The same kind of stone with the intervening particles of fel¬ 
spar of a red colour. (Note: the red colour in some of fragments 
from Gunong Mangkul has been pointed out above.) 
3. Fragments of pure compact quartz. 
4. An anomalous stone not found elsewhere, consisting of deter¬ 
minate fragments some of which were cylindrical others reniform 
and irregular with a tubular excavation extending through the whole 
length: the fracture approached nearest to a very compact, fine¬ 
grained sandstone, the colour was light red inclining to grey the ex¬ 
ternal parts, and in some cases intersecting lines, white. 
5. Amygdaloids consisting of numerous particles of quartz ce¬ 
mented by an oehreous earth of a brownish red colour of a loose testure. 
6. Compact ponderous Breccia of the same component parts. 
7. Compact Breccia of large fragments of quartz bedded in a 
yellow cement which appeared oehreous on the fracture. 
Between the mines of JKrassak and those of Messu the country 
is generally low and some tracts are partially inundated : these mines 
are dispersed through an extensive district extending to the boun¬ 
dary of the ocean and but little elevated above its level. Numerous 
works have been carried on here, some of the strata have extended 
to the sea shore and probably beyond it. 
Very near the discharge of the river of Messu, I met a vertical 
section of a mine lately worked ; under the soil followed a stratum 
of sand 3 feet deep and next to this one of clay of various colours 
10 feet; to the naked surface of this still adhered particles of quartz 
and fragments of Red-Iron-stone, exhibiting a characteristic view of 
their disposition in the stratum. 
Near the lower part of this section, on a different side of the same 
mine, I found a large space covered with clay in the highest state 
of purity in a deep layer, separating spontaneously when removed 
(according to the lines intersecting the surface) into fragments of 
a rhomboidal and pyramidal form with regularly defined sides. The 
colour is yellow, reddish or orange; it is highly unctuous to the 
touch, and adheres strongly to the tongue if applied to it. In no 
part of the island I found it in such apparent purity, and the small¬ 
est particle of sand is observed in it. 
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