94 Mineralogical Description of the Island of Banka. 



On another of the sides I remarked, 



1. Soil. 



2. Black clay massive. 



3. Sand adhering partially by means of a clayey cement. 

 4 Pure white sand. 



The difference between the two last mentioned layers was 

 very evident : in the third the proportion of clay was very abun- 

 dant, and united the particles of pure white sand to a mass which 



solid by drying. The fourth was a pure sand consisting 



of minute grains of quartz, most of which were transparent ; in 



« k *-*h -m * A a * 



distinction from the other, it was perfectly loose without any ad- 

 hesion of its particles. 



The manner in which the black clay is generally interposed 

 or intruded between the other strata deserves some attention, but 

 will more properly be considered elsewhere. 



The mines of Sunnie are situated near the northern boundary 

 of the district of the mines above mentioned. They are of the 

 large kind : the workmen had, at the time of my visit, nearly 

 arrived at the commencement of the stratum containing the ore, 

 after having penetrated : 



1. A stratum of soil, 



2. White clay mixed with a small proportion of sand, 



2 feet. 



becoming a solid mass by drying, . . 3 



u 



3. Coarse sand, consisting chiefly of fragments of crys- 

 tals of quartz in some places, intervening small 

 masses of clay, .... 



2 



u 



it 



4. Black clay in irregular masses, . . .2 



5. Fine sand, dispersed through particles of quartz and frag- 

 ments of decomposed granite rocks : here the ore commenced to 

 be thinly disseminated through the stratum, the lowest portion 

 of the layer which had been carried out from the last pit adjoin- 

 ing to the present work, had consisted of very large fragments of 

 decomposed granite, through which the ore had been plentifully 

 dispersed. The miners informed me that the vein of ore on 

 which they had been employed for three years, and which oc- 

 cupied the lowest part of the valley, had several times intersected 

 the course of the river which flows through it. 



On my track from the mines of Sunnie to Mampang, I was 

 gratified, for the first time, by the discovery of a rock of granite 

 in its original situation, in the midst of a forest and almost con- 

 cealed by a thick coat of moss. This directed my attention to 



the hill Ganten, with its appendages, which was near by the road. 



I found that the rock which forms the basis of this hill is of the 

 same kind. 



