26 DISTRIBUTION OF MINERALS IN SARAWAK. 



The most considerable quantity of ore has been gained, not by 

 vein-mining-, but by washing* in the felspathic clays flanking the 

 western aspect of the hill. These clays afforded pure stream 

 Cinnabar in great abundance, as well as hundreds of rich boulders 

 of ore-bearing rock that had been denuded from the upper parts 

 of the hill. This source of wealth, however, was limited, and 

 may be regarded as exhausted. 



A search for fresh deposits has been instituted from time to 

 time. Traces of Cinnabar have been detected behind the 

 Sibugoh mountain and in the Samaraham and Sadong districts ; 

 and traces of metallic mercury have been reported on good 

 authority at Marup in the Batang Lupar ; and at Gunong 

 Gading, a few miles to the west of Tagora, ore has been dis- 

 covered in situ, and is being worked. The Gading deposits 

 are altogether smaller and much poorer than those at Tagora. 

 The general geological features of the two hills are similar, but 

 the matrix at Gading is more siliceous and more highly 

 metamorphosed, though at the same time decomposing rapidly 

 on exposure to atmospheric influences, as is also the case with 

 the Tagora rock. The character of the Cinnabar differs from that 

 of the Tagora deposits, being soft and crystalline, and the ore in 

 the stream-washing is small and very friable, and so abundantly 

 mixed with iron-pyrites as to make it impossible to separate the 

 two minerals by simple hand- washing. 



As with the antimony there is evidence of the association of 

 minute quantities of quicksilver, so too, antimony (sulphide) has 

 been observed in juxtaposition with the Cinnabar in the same 

 fragment of veinstone at Gading. 



With regard to the origin of these deposits of Cinnabar, it is 

 almost certain that they were produced by the passage of heated 

 vapours bearing quicksilver and sulphur in a state of sublimation, 

 which were deposited by the cooling of the vapours as they 

 approached the surface of the earth. The peculiar and irregular 

 mode of deposition of the Cinnabar, and the facts that the lower 

 the miner goes the less abundant the ore becomes, aud that no 

 definite " run," or fissure vein, is observable, all point in this direc- 

 tion. It is confirmatory of this view, that the surrounding shales 

 and sandstones are all more or less highly impregnated with per- 

 oxide of iron, whilst in the metamorphic ore-bearing rock, iron is 

 scarcely visible except in the form of pyrites, i.e. in combina- 

 tion with sulphur, which can only have risen from below in a 

 state of sublimation, and has seized on the iron and collected it 

 in this form. Assuming a large proportion of sulphur in the 



