516 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [JlUie 17, 



I know, found in the Maestricht Beds ; but, according to Bronn, it 

 occurs also in the ' fitage Suessonien.' 



In a search for lodes of copper in the western part of Borneo, 

 north of Pontianak, made on behalf of private adventurers by Mr. 

 Everwijn, the strings of copper that were found, though very 

 rich, were too small to pay for working. There are also some poor 

 copper-lodes near the Singkarah Lake, in the mountains east of 

 Padang, in the Island of Sumatra ; but the veins, though large, are 

 too poor to be worked. 



A search for tin-veins was made in the Island of Blitong (Billi- 

 ton), by Mr. Akkeringa, one of our mining-engineers, in 1860-61, 

 with the following result : — at Brang no metalliferous veins were 

 found ; but on the Tadjouw Hill (goenoeng Tadjouw) a vein 4 to 5 

 feet wide, and containing much tin-ore, was discovered ; its exploi- 

 tation was commenced last year. Granite and elvan were found on 

 the south, and eurite (elvan) on the north of Tadjouw Hill. 



A large vein of manganese -ore (pyrolusite) occurs in porphyry, 

 close to the Nummulitic Limestone, in the south-eastern part of 

 Borneo. This manganese-ore would have been extracted for the 

 European market more than two years ago, had it not been for dis- 

 turbances in that part of the island. 



A limestone occurs in Timor Island (near Timor koeping) contain- 

 ing Encrinites in abundance*. 



Twelve years ago, when I first arrived in India, it was generally 

 considered that the stream-tin found in the Island of Banka was not 

 derived from veins in the granite of the island, but from mountains 

 on the continent of Asia, whence it had been washed down to 

 the bottom of the sea; and that the sea-bottom had been subse- 

 quently upheaved so as to form the Island of Banka. This sup- 

 position appeared to me erroneous, and I therefore endeavoured to 

 collect facts bearing upon the question. In 1853 I inspected all 

 the stream-works in the island, and found, in the district of Pankal- 

 pinang, three parallel veins running nearly east and west, one of 

 them containing tin-ore in grains, like those found in the stream- 

 works. In 1855, Mr. Akkeringa surveyed the Jeboes district, and 

 found grains of tin-ore disseminated in granite. I also found that 

 in every river which was streamed for tin the largest grains were 

 found nearest the hills, and that further away towards the sea they 

 gradually became smaller. Wow, as the rivers of Banka run from 

 the interior in all directions towards the sea, these facts proved that 

 the stream-tin is the detritus of the rocks and veins containing tin- 

 ore occurring on the island. 



* M. de Groot has sent a specimen of this limestone, and specimens of the rocks 

 and minerals he mentions, as well as of some fossils from the clay and the marly 

 sandstone of the tertiary formation of Java. The last-named specimens were 

 found near the Seela Hill (goenoeng Seela), in the Preanger regency, about 2000 

 French feet above the level of the sea. He has also sent some specimens of fossil 

 Mollusca from the clay separating two beds of workable coal in Borneo. The 

 rocks and minerals are in the Museum of Practical Geology, and the fossils 

 in the Museum of the Geological Society, having been presented by Sir E. I. 

 Murchison, K.C.B., F.R.S., &c.— Edit. 



