BY THE REV. J. E. TENISON-WOODS, F.G.S., F.L.S., &C. 1193 



with well defined stratification. Towards the gaol and at the foot 

 of the quarry hill the paleozoic formation may be seen, with much 

 contorted bedding, and ribbon like structure, forming bands of red, 

 yellow, and white. It is evident that the present river valleys 

 have all been cut through this rock on to the gi-anite and that the 

 materials forming the drift have been derived from both. I consider 

 that the paleozoic clays play a most important part in connection 

 with the tin deposits, according to what has already been said. 

 The rich tin sand has its matrix in the granite, but more 

 abundantly at its junction with the paleozoic clays than elsewhere. 

 All the tin workings at Thaiping are in drift, and therefore in 

 what has at one time or another been a portion of a river valley. 

 The depth of the drift is never more than 30 feet and sometimes 

 much less. Near the range it is less and the gravel coarser, often 

 mingled with boulders of granite of a ton or so in weight. The 

 tin sand is also coarse. The general run of the sections is : — 

 1. Alluvium of yellow clay. 2. Sand of yellow colour with 

 occasional drift wood of large size. 3. Blue and yellow clays with 

 infiltrations of much bright red oxide of iron. 4. Coarse waterworn 

 gravel composed of granite and various coloured quartz and felspars. 

 5. Tin sand, in clay or sand or pipeclay. The tin is fine in 

 quality. The crystals usually not much abraded and seldom 

 much larger than two millimetres in diameter. In speaking of tin 

 ore or tin, tin sand, cassiterite or oxide of tin (Sn 02) is meant, 

 that is to say, pure metallic tin 78'62 and oxygen 21 38. It 

 occurs in short prisms with four or eight sided pyramidal 

 summits or complicated by twin crystals. Generally however it is 

 so abraded and broken as to leave scarcely any trace of crystalli- 

 zation. It is blackish like graphite, sometimes reddish brown or 

 ruby red, often transparent but rarely colourless. Its fracture is 

 hackly and its lustre vitreous. In many specimens of fine tin from 

 Thaiping small broken prisms of transparent olive green are not 

 uncommon. In this there appears to me to be a distinct difterence 

 between the tin ores of Perak and those of Australia, especially 

 those of Victoria. The latter contain a much larger proportion of 

 hyacinth-red crystals. Samples from the above named countries 



