Page:Journal of the Straits Branch of the Royal Asiatic Society (IA journalofstrait121878roya).pdf/53

Rh the Borneo Company to report on the antimony mines, is decidedly in favour of the aqueous, as against the igneous theory of the origin of the antimony.

. The mineral was discovered in situ about seven years ago, by the indefatigable exertions of Messrs. Helms and Walters of the Borneo Company Limited, who prospected over the whole of Sarawak Proper, and ultimately succeeded in tracking the small fragments of cinnabar that are scattered over the district, to a hill on the right bank of the Staat river, and between it and the Sibugoh mountains.

During the progress of the exploration, a rough but serviceable sketch-map was executed, embracing Sarawak Proper and Upper Samaraham, on which the positions of the principal deposits of antimony and cinnabar will be found accurately marked.

The Hill containing the cinnabar—for it is in this form as usual that the quicksilver occurs—is known by the name of Tagora, and is, or rather was, a steep twin-peaked mass of semi-metamorphic rock, rising to an elevation of about 800 ft. above the sea-level, in the upper parts of which the ore is found deposited capriciously in strains, pockets and strings, with now and again a little metallic mercury.

The component rocks are argillaceous shales, with sandstones interbedded; these have been very extensively disturbed and contorted, and the former are as I have said, partially metamorphosed into an impure state, glittering with cubical iron pyrites, and, in the higher portion of the hill, full of cutters of carbonate of lime. Nodules of black shale occur here and there in the state which is, in appearance, amygdaloidal, through being often thickly spotted with cale-spar, baryta, and pyrites. Some layers of sandstone which I observed cropping out at a very high angle on one of the peaks, did not seem to have been affected in the same degree with softer shales by the metamorphic action, and still retained their normal structure, though hardened to such a degree as to be most refractory in working.

The ore is found in the slate, rarely in the sandstone, and, as is the case with all known deposits of Cinnabar, is distributed with great irregularity in the matrix. Hence the yield has proved extremely variable, and at times the ore has seemed to be lost altogether. No such thing as a lode can be said to exist, though short strings are met with. One of these attained a face of six inches, and was traced down to a depth of many fathoms.