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R. A. F. PENROSE 



elsewhere the rock is simply impregnated with particles and 

 crystals of cassiterite over certain areas. The tin is associated 

 with quartz, tourmaline, fluorite, and the other minerals already 

 mentioned, especially iron pyrites and arsenical pyrites, which 

 often occur in very considerable quantities, and with smaller quan- 

 tities of chalcopyrite. At Sorakai, some three miles southwest of 

 Ipoh, two shafts were sunk on small seams of tin ore in the 

 granite by an English company, but operations did not prove 

 profitable and the works are now closed. 



Tin in the limestone is probably rarer than in the granite, as 



Fig. 4. — Section showing occurrence of lin-bearing alluvium at Chongkat Pari, 

 Perak, Malay peninsula. 



Chongkat Pari was the only case seen or heard of by the writer 

 where it had been clearly proved to exist in that rock, while tin 

 in the granite is of common occurrence. Chongkat Pari is two 

 and a half miles southwest of Ipoh, and the region has been 

 extensively worked for alluvial tin. The bed-rock is limestone, 

 and the alluvium occurs in hollows and caves in the leached sur- 

 face of this rock. (See Fig. 4.) It is from i to probably 20 

 feet in depth, of a reddish-brown color, and contains many large 

 ferruginous masses, probably resulting from the oxidation of 

 iron-bearing sulphides common in the limestone. At the mine 

 of the Leh Chin Tin Mining Co. at this locality tin occurs not 

 only in the alluvium, but also in situ in limestone. It is found 

 along a zone of fracturing, marked sometimes by sheeting, run- 

 ning in a general direction of north northeast and south south- 

 west, and dipping steeply to the west northwest. The ore 

 occurs as cassiterite along the zone of fracturing, sometimes as 

 an impregnation in the limestone, sometimes as lenses or irregular 

 pockets from 4 to 24 inches in width, and sometimes along the 



