Page:Journal of the Straits Branch of the Royal Asiatic Society (IA journalofstrait121878roya).pdf/51

Rh By far the principal part of the antimony, however, is afforded by the sulphide or common gray antimony, which occurs both in the form of lodes in the limestone rock, and in deposits of rolled boulders in the valleys contiguous to the hills bearing these lodes. These latter sources of the ore are now worked out, and the supply is dependent almost wholly on the vein-mining. The percentage in ores werkedworked [sic], runs from 18 to 80 per cent. The Ahup ore, of which only a few boulders have been met with is the richest known, giving a percentage of 80 per cent of pure sulphide. But this is exceptional; in practice the ores if very rich or very poor are mixed with stuff of average quality (No. 2.) preparatory to smelting. The bulk of the ore has a distinctly lamellar structure, and commonly has a shining steel-gray lustre when freshly fractured; sometimes it is iridescent, presenting a rich play of blue, violet and crimson hues like variegated copper-ore. The poorer varieties exhibit a starry pattern of needless radiating through the white veinstone; or the antimony will traverse the matrix in long slender spikes, or be disseminated in specks in the poorer sorts. More rarely one finds masses of tangled acicular crystals which are now and then endomorphous in hexagonal prisms of quartz crystal. The gangue is generally siliceous, sometimes amorphous, sometime crystalline, or, less commonly calc-spar (rhombic); and when a vein of white siliceous gangue is followed into the rock, in invariably runs into a dark gray amorphous siliceous veinstone, of extreme hardness and with little or no oerore [sic] in it. This dark-coloured veinstone appears with the antimony in all situations and the oerore [sic] is always intimately mixed with it, the stone itself when magnified being seen to be thoroughly impregnated with the sulphide in the form of minute needles. As a general rule vein-ore is rich, but runs poorer as the lode is worked in, the block spar gradually preponderating and ultimately replacing the antimony altogether. Lodes in which the matrix is calc-spar are rarer those in which the gangue is siliceous.

The arrangement of the contents of a vein often differs entirely in portions only a few feet apart: calc-spar, black-spar, crystalline white quartz, and antimony being intermingled confusedly one with another—each one running for a few feet or inches in a narrow ill-defined band and then being lost in some other; but in other lodes uniform bands of calc-spar or quartz will be found coating the walls of the fissures, with a single rib of ore running between. Instances have occurred of large masses of sulphide rich on the surface being found, when worked down to the limestone, to terminate in an insignificant vein of very poor ore; exactly as if there had been a continued