90 Minera logical Description of the Island of Banka. 



metallic fracture) are of a dark brown color, laminated or cellular, 

 the excavations exhibiting a dark shining surface and resembling 

 a substance which has undergone fusion and suddenly cooled ; 

 the ochreous fracture is generally porous and the color intensely 

 red. Both are a rich iron ore, and their analysis and accurate 

 description will be given in the sequel. 



The following nine valleys exhibited similar appearance. The 

 red ironstone in great variety ; and sand, apparently of diiferent 

 colors, from the clayey particles that are accidentally mixed with 

 it; several of them transmit rivulets, others bear the marks of 

 an accumulation of water after rains. 



In the ascent after leaving the tenth valley, the road crosses a 



very extensive layer of sandstone. The color, in general, is light 

 blue or inclining to grey ; some parts are covered with a yellow- 



ish ochreous crust. It is divided or separated by rightlined fis- 

 sures, which appear on the surface in delicate lines or streaks 

 crossing each other in various directions : when struck, it sepa- 



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rates at these lines, in fragments of every variety of configuration 

 with flat sides and sharp angles, forming squares, lozenges, pyra- 

 mids and oblique parallelograms in endless variety. The adhe- 

 sion of its particles, in its natural situation, is not strong and 

 many portions are friable ; by drying, it acquires a considerable 

 degree of hardness. On this layer of sandstone I found, dispersed 

 in various parts, loose fragments of a substance purely siliceous 

 consisting of minute crystals of quartz closely united into a 

 brittle mass, divided and separating by regular fissures, but 

 mostly in planes or slabs with even surfaces. In the eleventh 

 and twelfth valley are dispersed large loose fragments of red 

 ironstone, similar to those above described: they both transmit 

 small rivulets. After the thirteenth descent, follows that district 

 in which the mines are at present worked. Its* boundaries and 

 extent cannot be defined, but the most productive strata of tin 

 ore have been found near the central parts of this peninsula, at 

 the junction of the districts of Sungie-bulu, Klabet and Tenga 

 embracing an irregularly oval space, whose longest diameter is 

 about six miles, sending off arms in various directions, particularly 

 towards Klabbet-lama or to the northeast. Towards the north and 

 northeast the plain is surrounded by the ranges of hills above 

 mentioned; m the southwest and south, it unites with the allu- 

 vial hills, which stretch obliquely across this part of the island, 

 and its south and southeast extremities extend to that large des- 

 ert, surrounding the mountain of Maris, which has been imper- 

 fectly investigated. 



This district, upon the whole, is level or variegated with very 

 gentle risings : but like most parts of Banka, it is so completely 

 covered with vegetation, that in no place can a large extent of 

 surface be taken into view at once. 



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