﻿440 ME. J. B. SCRIVENOK ON THE |A U &* r 9 I0 r 



Petrological Details. 



(i) 



Argillaceous schists, frequently mineralized. 



Localities numerous. 



(ii) 



Fine-grained sandstone and sandy schists, sometimes 



mineralized, and generally containing tourmaline. 



Localities : near Batu Grajah ; Siak ; Lahat ; open cut behind 



Redhills ; Gopeng (but no tourmaline-corundum rock). 



(hi) 



Black carbonaceous schist. 



Localities numerous. 



(iv) 



Black, carbonaceous, fine-grained, siliceous rock, with a trace- 



of radiolarian structure. 



Locality : open cut behind Eedhills. (PL XXXI, fig. 5.) 



(v) 



Light-coloured rocks: no tourmaline or corundum. 



Localities various. 



(a) Under the microscope, this is seen to be made up entirely of bodies 

 that strongly suggest oolitic grains. They sometimes show concentric 

 structure. The rock, however, is siliceous, very fine-grained, and contains 

 abundant white mica in minute flakes. There is some pale yellow dust present. 

 (PI. XXX, fig. 1.) 



(b) The base of this rock is siliceous and contains mica like (a). It is full 

 of similar round and oval bodies, and also contains round bodies arranged 

 in lines. , 



(c) A fine-grained siliceous rock, with flakes of mica. It is much veined, 

 and suggests some of the altered cherts of Pahang (see pp. 445, 446). 



(d) Numerous round and oval bodies, many showing a dark centre and 

 lighter border, the former being caused by black dust in greater quantity than 

 in the border. The rock contains carbon : the base is very fine, and apparently 

 siliceous. A few veins of tourmaline occur in this rock. (PI. XXX, fig. 2.) 



(e) A carbonaceous rock strongly suggesting an altered chert. Numerous 

 obscure markings. 



(/) The base is very fine-grained and crystalline, composed apparently of 

 silica and mica. It is schistose, the schistosity being shown by bands of white 

 opaque material. Pyrite crystals, surrounded by a clear border, are abundant, 

 and there are numerous small, clear, round bodies with a core of pyrite. 



(vi) 



Rocks with tourmaline only. 



Localities various. 



(a) A very fine-grained siliceous rock, with minute prisms of tourmaline and 

 veins of micaceous material. Coarse black dust and perhaps carbon are present. 



(b) Like (a), but with round bodies enclosing black dust. 



(c) The base is very fine-grained, and contains round bodies faintly marked 

 by tourmaline grains. 



(d) This is very fine-grained, and contains white dust. It is veined with 

 pale yellow tourmaline. 



(e) The base is fine and siliceous, and contains minute prisms and veins of a 

 mineral that is probably colourless tourmaline (achroite). There are numerous 

 round and four-cornered clear spots, composed probably of achroite also, and 

 containing sometimes a yellow mineral that could, not be determined. 



(f) This is composed entirely of brown and bluish tourmaline. 



