collier.] TIN OEES OF MALAY PENINSULA. 47 
Peninsula for a distance of 900 miles, but the principal mining- district 
is located about 300 miles northeast of Singapore, and is known as the 
Kinta district. The district comprises a more or less inclosed valley 
about 40 miles in length, extending in a north-south direction, about 
30 miles in width at its south end and about 5 miles wide at its north 
end. The valley includes some lower mountains and areas of lime- 
stone, surrounded and partly covered with great tracts of alluvium. 
Much of this alluvium contains oxide of tin, or cassiterite, in particles 
and fragments of varying size, forming what might be termed "tin 
placers,' 7 in which the tin occurs in different ways. Sometimes it is 
scattered through it from top to bottom in comparatively uniform 
quantities; sometimes it is in layers or pay streaks separated by barren 
ground; sometimes it is richest on the bed rock. As a general rule, 
however, there is a covering or " overburden " of barren alluvium from 
10 to 40 feet or more in thickness above the tin ground. The best 
ground occurs immediately at the foot of the mountains. Higher 
up it is often richer, but of small extent, while farther away it is 
thicker, but of lower grade. The ordinary tin-bearing beds vary from 
1 to 30 feet in thickness, though sometimes they reach over 100 feet. 
In one instance the tin-bearing formations extend from the surface 
down to a depth of from 5 to 30 feet, without any barren overburden. 
In another instance large open pits in the alluvium of the river valley 
show tin-bearing strata, varying from 2 to 10 feet in thickness, with a 
barren overburden about 40 feet in thickness. In another instance 
the overburden is from 30 to almost 40 feet in thickness, and the tin- 
bearing ground below has been penetrated 140 feet vertically without 
reaching the bottom. In the mountains near its source the ore is 
angular and in comparatively large fragments, sometimes from an inch 
to a foot or more in diameter. Farther down the hill it becomes more 
and more rounded and finer in grain. 
Most of the mines are operated by Chinamen, and the labor is per- 
formed by coolies from southern China. The tin-bearing alluvium is 
worked mostly in open cuts or large pits, except where the covering 
or overburden is very thick, when shafts are sunk to the tin stratum. 
The average depth of the working is about 40 feet, and the greater 
depth can not ordinarily be reached on account of water in the pits. 
It is a common thing to see water raised from these pits by a rude 
treadmill pump worked by the feet of Chinese laborers. 
The pay gravel dug from the bottom of the pit is carried up an 
incline to the surface in baskets hung on either end of a stick carried 
on the back of a Chinaman. It is then dumped into wooden troughs, 
supplied with running water, and, if necessary, stirred with a shovel 
until washed into the sluice boxes. These boxes are from a few feet 
to several hundred feet in length, and are built of wood or cut in the 
sandy clay of the region. In the description of them no mention is 
