mineraIjOgical description of the island of banka. 403 
nig, it acquires a considerable degree of hardness. On this layer of 
sandstone I found, dispersed in various parts, loose fragments of a 
substance purely siliceous, consisting of minute crystals of quartz 
closely united into a brittle strong mass, divided and separating by 
regular fissures, but mostly in planes or slabs with even surfaces. 
In the eleventh and twelfth valley are dispersed large loose fragments 
of red-iron-stone, similar to that above described : they both transmit 
small rivulets. After the thirteenth descent follows that district in 
which the mines are at present worked. Its boundaries and extent can¬ 
not be defined, but the most productive strataof tin-ore have been found 
near the central parts of this peninsula at the junction of the districts 
of Sungie-bulu, Kl&bbet and Tengd, embracing an irregularly oval 
space whose longest diameter is about six miles, sending off arms in 
various directions, particularly towards Kldbbet-ldmd or to the north 
east. Towards the north and north-east the plain is surrounded by 
the ranges of hills above mentioned ; in the south-west and south, it 
unites with the alluvial hills, which stretch obliquely across this part 
of the island, and its south and south-east extremities extend to that 
extensive desert, which surrounds the mountain of Harass, and which 
has imperfectly been investigated. 
This district, upon the whole, is level or variegated with very gen¬ 
tle risings : but like most parts of Banka it is so completely covered 
with vegetation, that in no place a large extent of surface can be 
taken into view at once. 
Of all the mines that are worked at present, in this district, those 
of Jebus or Anten are the most considerable ; they are divided, ac¬ 
cording to their situation, into those of the Upper-furnace , and of 
the Lower furnace, in the former two, and in the latter three large 
mines are worked at present, besides ten small ones distributed 
through both districts. 
The large mines of the Upper-furnace district are those of Sun- 
gie Tango and Suntay, and of the Lower-furnace distinct, those of 
Sungie-Bitlak , Tdyndni and Seam: the ten small mines of both 
districts are those of SunJco, Sunyu , Swising, Sunwad, Sunwing , 
Sunhawa, Soktjoy, Tenpo, Assuri, and Atshey, 
