DISTRIBUTION OF MINERAL SARAWAK 23 



By far the principal part of the antimony, however, is afforded 

 by the sulphide or common g'ray antimony, which occurs both m, 

 the form of lodes in the limestone rock, and in deposits of rolled 

 boulders in the valleys contiguous to the hills bearing 1 these lodes. 

 These latter sources oi the ore are now worked out, and the sup- 

 ply is dependent almost wholly on the vein-mining*. The per- 

 centage in ores werked, runs from 18 to 80 per cent. The Ahup 

 ore, of which only a few boulders hav ebeen 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 struc- 

 ture, 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 finnds masses of tang'led 

 aeicular crystals which are now and then endomorphous in hexa- 

 gonal 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 silice- 

 ous gangne is followed into the rock, in invariably runs into a 

 dark gray amorphous siliceous veinstone, of extreme hardness 

 and with little or no oer in it. This dark-coloured veinstone 

 appears with the antimony in all situations and the oer 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 pre- 

 ponderating' and ultimately replacing the antimony altogether. 

 Lodes in which the matrix is calc-spar are rarer those in 

 which the gangueis siliceous. 



The arrangement of the contents of a vein often differs entire- 

 ly in portions only a few feet apart : calc-spar, black-spar, 

 crystalline white quartz, and antimony being intermingled con- 

 fusedly 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 larg^e 

 masses of sulphide rich on the surface being found, when work- 

 ed down to the limestone, to terminate in an insignificant vein of 

 very poor ore ; exactly as if there had been a continued overflow- 



