﻿Vol. 66.'] TOURMALINE-CORUNDUM ROCKS OF KINTA.. 445 



(4) Carbon is a frequent constituent. 



(5) Where sandstone or sandy schist is present in any quantity among the 

 beds overlying the limestone, the tourmaline-corundum rocks are rare or 

 absent. 



(6) In the open cut behind Redbills, a black, carbonaceous, fine-grained 

 siliceous rock was found, whicb, if mixed with a number of specimens of 

 radiolarian chert from Pabang could hardly be distinguished from them, 

 although it must be admitted that the radiolarian structure observable in this 

 rock is not so clear as in the Pabang rocks. 



(7) Some of the light-coloured pebbles and boulders found with the tour- 

 maline-corundum rocks strongly resemble bands of fine silty rocks associated 

 with the Pabang cherts. 



(8) The tourmaline-corundum rocks are evidently derived from certain beds 

 forming part of a series overlying massive beds of limestone. 



I will not say that these facts show that the original rocks from 

 which the tourmaline-corundum rocks have been derived were of 

 deep-sea origin, since such a statement would open up a question 

 that cannot be discussed here, although it is of especial interest 

 to those who have studied the geology of the East Indies ; but I 

 may point out that there is good reason to suppose that the 

 tourmaline-corundum rocks were derived from rocks which were laid 

 down under conditions similar to those that obtained when radio- 

 larian cherts and associated carbonaceous rocks were deposited else- 

 where. Such rocks occur in Pahang, 1 the cherts generally containing 

 carbon, and there the evidence in the field points to the chert and 

 carbonaceous shale being closely connected with Carboniferous 

 or Permo-Carboniferous limestone and calcareous shales, together 

 with contemporaneous volcanic rocks. 



But, while it is more than probable that the bulk of the tour- 

 maline-corundum rocks were derived from beds younger than the 

 crystalline limestone of Kinta, there is evidence to show that some 

 may have been formed by the extreme metamorphism of beds that 

 are still to be seen intercalated with the limestone on the west of 

 Changkat Pari, near Ipoh. These beds occur as thin partings in 

 massive limestone pinnacles, that were originally covered by sandy 

 alluvium. They are soft, and are slightly greasy to the touch. 

 Some of them are very light in colour, with dark spots, caused by 

 an accumulation of black dust. One bed is very dark and resembles 

 serpentine, its darkening being due to abundant black dust. The 

 ground-mass of these rocks appears to be composed of a tine micaceous 

 mineral and isotropic matter. In some of the lighter-coloured 

 partings minute white spots are seen, which, under the microscope, 

 bear a remarkable resemblance to the smaller bodies found in 

 the light- coloured rocks accompanying the tourmaline- corundum 

 rocks. Nearly every body is surrounded by a clear ring that is 

 found, under a high power, to consist chiefly of isotropic material 

 like that in the ground-mass, while the body itself is composed 

 of white, opaque, hair-like bodies and dust. Sometimes the 



1 These rocks were described in my ' Report of Progress : Sept. 1903- 

 Jan. 1907' (F.M.S.) Kuala Lumpur, pp. 2&3. 



