94 
GEOLOGICAL FEATURES OF SINGAPORE. 
easily yield to the knife. It is not magnetic in the mass, but, when 
pulverized, grains of magnetic iron appear. The powder is a dark 
brown earth. It resembles a good deal the very magnetic ironstone 
found by me in the Tavoy Province, Tenasserim, in 1825. But 
amongst the sand and gravel in which these ironstone masses lie 
imbedded, 1 have found grains of highly magnetic oxidulous iron 
ore. 
There is a good deal of this iron ore upon Bukifc Juhltong, 
which is a hilt belonging to me in Province Wellesley, Pinang; and 
it was there generally used by the Malays to make iron. But it 
was not found rich enough to repay the trouble of working it. 
The depth at Singapore of the iron clay and conglomerates rare¬ 
ly exceeds six feet, the average being about three feet, and they 
very seldom extend in any given locality over a greater surface than 
three or four acres. But where the ironstone does not appear su¬ 
perficially, it will pretty generally be discovered below r , at the depth 
above given, provided the incumbent soil be of a reddish hue. 
It is most common at the extremities of the ridges, and on their 
summits, in their lower slopes and in their hollows. In the latter 
case it is thickest in the centre, fining off towards the edges, but of¬ 
ten terminating abruptly at its greatest thickness. 
Where the ironstone stratum contains a large portion of the me¬ 
tal it is very stcril, but where the oxide of iron is not in excess 
the soil there becomes the most fertile which the island possesses, 
although the limit is very confined. 
Captain Franck!in notices that the amygdaioidal iron clay at Bartia 
in India is steril and bare in some places, and apparently highly 
productive in others.* 
It appears occasionally as if running in a superficial vein, but this 
seems to be merely owing to its superior hardness to the vertical 
strata which were in contact with it, and which have been disin¬ 
tegrated. The red iron ores chiefly belong to the secondary forma¬ 
tion, those of a dark brown or black colour chiefly but not exclu¬ 
sively to primitive ones.*i* To this last class, the one we are des¬ 
cribing bears a close affinity. 
The specimens before me are 
* Page 70, 
d* Phillips Minerals p. 47? 
