148 R. A. F. PENROSE 



percolating along the bedding planes. This special locality was 

 not visited by the writer, but specimens of the ore and the rock 

 were seen. 



Origin of the ti?i deposits of the Kinta district. — The question of 

 the origin of the tin deposits includes the occurrence of both the 

 tin in the alluvium and the tin in the rock. The tin in the 



Fig. 6. — Limestone bluffs southeast of Ipoh, Perak, Malay peninsula. 



alluvium has clearly been derived by erosion from the tin in the 

 rock, as is proved by the following facts : 



1. Tin in noticeable quantities is a constituent of some of the 

 rocks of the region, especially the granitic rocks and sometimes 

 the limestone. 



2. The mass of the alluvium is composed of materials derived 

 largely from the decay and erosion of the tin-bearing rocks of 

 the region, and contains numerous pebbles and bowlders of these 

 rocks. 



3. Frequently granitic fragments, similar to the granite in 



