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On the Occurrence of Plathia and Diamonds in Borneo. 



The occurrence of platina in the East Indian Archipelago 

 is but little known, and it is probably quite new to many that 

 this metal is actually obtained there in large quantity.* Upon 

 this subject we have acquired accurate information from the 

 late Dr Ludwig Horner, the son of the celebrated astronomer 

 and voyager Horner of Zurich. The details deserve to be 

 better known, and are contained in the Verhandelingen van 

 het Batavlaasch Genootschap van Kunsten eri JVetenschappen . 

 xvii Deel. Batavia, 1839, p. 89. At the south-eastern ex- 

 tremity of Borneo, named Tanah Laut (Seeland), there ends 

 a mountain-chain which accompanies the course of the great 

 river of Banjermassing, and which has been traced to the 

 north of the Equator. The most southern portion of tlie 

 mountain range is termed the Ratoos Mountains, whose highest 

 summit rises 31G8 Parisian feet above the sea, and these are 

 chiefly composed of serpentine, diorite, and gabbro. The 

 valleys and the base of these mountains are covered by a thick 

 deposit of red clay, in which there is an imperfectly defined 

 bed of white quartz pebbles. In the valleys the red clay is 

 from 10 to 20 feet deep, and the bed of quartz pebbles is from 

 1 to 4 feet thick. It is this deposit which contains the gold 

 in extremely small plates, associated with a large quantity of 

 grains of magnetic iron-ore, and every where with small grains 

 of platina, as well as of iridium and osmium, but not of pal- 

 ladium. The strata repose directly on serpentine, and are evi- 

 dently derived from it ; the red clay having had its origin from 

 the rock itself, and the quartz from the quartz veins which 

 traverse the serpentine in great numbers. This is in the 

 district of Poelo (Pulo) Arij, where 150 Chinese wash out 

 yearly 750 tael of gold,t whose value amounts to 45,000 Dutch 

 florins. 



* The only other part of Southern Asia wliere tliis metal has been met 

 with is Ava. 



t A tael is 2 ounces. 



