SARAWAK MINERALS.—BY J. S. GEIKIE. 195 
are found all the deposits of the economic minerals 
which the country produces, except those of coal and 
oil. 
In this district occur—Antimony, Arsenic, Gold, 
Cinnabar and. Diamonds, whilst coal is found at 
Sadong, Lingga, Brooketon, etc. and oil at Miri and 
Brooketon. Of these minerals the Diamonds are found 
in the Alluvial ; the Coal, Oil and Cinnabar in the 
younger Shale and Sandstone series, whilst the other 
metals occupy a geological horizon which approxi¬ 
mates to the junction of the Limestone and Sandstone 
series. 
Small deposits of Antimony ores occur in different 
parts of the country above this horizon but have so far 
proved to be of no economic importance. 
Native Elements. 
Diamond .— Diamonds are found in the Upper Sadong 
and in the left hand branch of the Sarawak River, 
where they occur either in the present beds of the 
streams or in the older alluvial forming the banks. 
The stones found are mostly small and full of flaws. 
Search for these is carrried on in a very desultory 
manner by Malay fossickers who confine their attention 
chiefly to the beds of the streams, which can only be 
worked during dry weather. 
There is no direct evidence of the origin of these 
stones but it is possible that they may be derived from 
the disintegration of the beds of conglomerate through 
which these rivers flow in places as at Pangkalan 
Am pat. 
In support of this it may be noted that Diamonds 
are also found just over the Sarawak border in the 
Skiyam River whose waters also cut through similar 
conglomerate beds. 
Arsenic.-- Occurs in Upper Sarawak and more parti¬ 
cularly at Bidi, where large reniform masses are fre¬ 
quently found in the limestone fissures along with Gold 
and Antimony Ores. 
Nowhere does It occur in quantity sufficient to make 
it of much commercial importance ; in fact its presence 
