92 Miner alogical Description of the Island of Banka. 



2. Sand mixed with mould (containing trunks of trees 



in a recumbent position ; and perforated by deep 



roots), . 

 Yellow clay in small irregular layers alternating 



9 feet. 





with dark colored sand, • . ♦ " 1 foot. 



4. White clay, 



5. Black clay massive, 



6. Coarse sand. 



6 inch. 

 1 foot. 



The miners were at this time engaged in carrying out these 



different strata ; they had penetrated nearly fourteen feet below 

 the surface, and from the disposition of the vein of ore, with 

 which they were acquainted by the experience of the last pit, 

 they expected to arrive at it after having descended about six 

 feet more. On the surface remaining exposed from the former 

 works, I observed very large fragments of a glistening white 

 stone consisting of quartz and feldspar mixed nearly in equal pro- 

 portions. Some of them were more than twelve inches in diam- 

 eter. If force was applied they separated at fissures into frag- 

 ments with regular sides. They had remained after the washing 

 of the ore ; the fragments of stone which remain, after this pro- 

 cess, at the sides of the canals or aqueducts, demonstrate clearly 

 the composition of the stratum in which the ore is found, and I 

 made it a rule to examine them in every mine I visited, and to 

 collect specimens of the varieties. 



At this place I found, besides the large fragment above men- 

 tioned, smaller particles, diminishing gradually to the weight of a 

 few grains of the same kind ; they all had a disposition to sepa- 

 rate into fragments with regular angles. In some cases the par- 

 ticles of feldspar were in a state of decomposition and formed a 

 white powder resembling chalk ; it was not in the least affected 

 on the application of the strong acids. Small crystals of pure 

 quartz were mixed with this white powder. 



Besides these, I found at the aqueduct, sandstone in small frag- 

 ments, resembling that above described. An aggregate stone or 

 conglomerate in laminae, composed of particles of quartz united 

 by a yellow, ochreous iron-earth : to several of these the particles 

 of tin ore were still found adhering, and irregular fragments and 

 crystals of pure quartz of various shades of color. 



In proceeding from the district of the Lower to the Upper fur- 

 nace one perceives, on the road, the vestiges of many of the old 

 mines : they form a contrast, though by no means a pleas;nit one 

 with the abundant vegetation of the island; the places of the 

 small mines present a naked uneven surface, covered with the 

 remains of the former works, to which the shining particles of 

 quartz mixed with the sand impart a peculiar aridity; the place 

 of the large mines is known by extensive chasms alternating with 

 irregular hillocks. It requires however, but a short time in 



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