at Grogo and Sikunyit; and it has been observed in traces between Ahup and Gumbang, at Sirin in the Samarahan, in the Sadong district, at Marup in the Batang Lupar, and in the Intabai and Poi tributaries of the Rejang river, and one good specimen of sulphide has come under my notice from the Kagan districts of the Upper Rejang.
These wide-spread traces cannot be referred to a single centre of dispersion such as it might be supposed the Upper Sarawak field would present. They point to the presence of one or more undiscovered accumulations of antimony ore to the east of Sarawak Proper, though whether within the boundaries or at a short distance beyond, cannot now be said. In Kanowit the traces are tolerably abundant, but their great distance island renders it vain to hope they will be followed up for many years to come, if at all.
The ores commonly worked are native antimony; gray sulphide, and the "oxide" or "red ore" (oxy-sulphide). Native antimony occurs in the form of worn rounded pebbles in alluvial flats in the immediate vicinity of the vein-bearing limestone, and especially in the gullies and crevices so characteristic of this rock which are always more or less filled with a debris of clay and fragments of veinstone and ore. My brother—to whom I was indebted for many of these notes—informed me that he once observed native antimony forming part of a vein, and in this single instance it was scattered throughout a small horizontal lode of the sulphide. The ore in this form is not found in large quantities, but as it contains a minimum of impurities, approaching more nearly to regulut of antimony than any of the other varieties, and therefore requiring no preparation before being exported, it is always secured where met with. The Busan hills have proved the richest depository of this ore.
The oxide, like the foregoing ore, is generally obtained in rolled fragments and pebbles which are often seen to be only blocks of sulphide, partially oxidized, and preserving their original lamellar structure. It is found in the same situations as the native antimony, but in much larger quantities. It has been hitherto exported in its rough state, and is the least valuable of the ores of antimony owing to the difficulties it presents in reduction. The largest boulder of which I have heard weighed some 8 cwt., but the fragments are almost invariably small, weighing from a pound to thirty or forty pounds. The chief supply has been obtained from Boan, Piat, and Paku localities around the base of the Busan bills.
