160 Lieut. J. B. Scrivenor — Origin of Clays and 



of a secondary nature. Tourmaline-corundum rock occurred near 

 by. The earlier work on this lode was underground, but now there 

 is an open-cast mine on the junction. On the one hand is a granitic 

 mass rich in kaolin and traversed by tourmaline veins, one 

 sufficiently well preserved to show a small fault ; on tiie other, deep- 

 red clay in which an apophysis of granitic vein-material was once 

 seen, itself traversed by tourmaline veins. One may argue that 

 away from the Junction bedded shales and harder rocks might be 

 disorganized over limestone so as to simulate boulder-clay, but at 

 the granite junction, where the granitic rock is equally soft and 

 contains clearly defined tourmaline veins, the bedding of soft and 

 hard rocks ought to be preserved. But it is not preserved, and the 

 inference is that it never existed. 



But away from the junction also there has been evidence against 

 the clay being disorganized shale. At least one vein of ore has 

 been worked open-cast with a course that could be easily followed. 

 How could this be preserved if the clay and boulders are broken-up 

 hard and soft strata ? 



Even more striking is the evidence at Tekka and Gopeng, where 

 there are good exposures of the junction between gi'anitic rocks on 

 the edge of the Main Range mass and clay at Tekka, while on the 

 Ulu Gopeng portion of Gopeng Consolidated is a junction with 

 schists. 



These schists are exposed on old workings at the top of 

 a steep hill overlooking the town of Gopeng. They are clearly 

 bedded and dip at a very high angle to the west. Sandy phyllites 

 are common; tourmaline-schist and actinolite-schist occur. Both 

 brown and white mica occur. The soil above them contains 

 ferruginous masses showing the structure of the schists they have 

 I'eplaced on weathering. Quartz veins are abundant. 



The clay at the junction with the granite on the Tekka Ltd. mine 

 and on mines further to the south should, if it is the result of the 

 extreme weathering of schists, still show some resemblance to the Ulu 

 Gopeng sections. The clay cannot be schist that has become a dis- 

 organized mass through movement because at the junction tourmaline 

 veins have been traced into it ; and moreover there are other veins 

 found sometimes parallel among themselves, but sometimes brecciated 

 bv movement, which are the effect of alteration by the granite. 

 Under the microscope these veins are found to consist chiefly of 

 white mica and fluorite in minute particles. In some veins 

 corundum, spinel, and blue tourmaline occur also ; and it is 

 significant that whereas the tourmaline in the Ulu Gopeng schists 

 is brown, that in the clay is blue, and of a shade pale enough to be 

 distinctly recognizable in a hand specimen. Only a few grains of 

 brown tourmaline have been obtained by washing a quantity of clay. 

 Moreover, the clay at the junction shows lamination with bright 

 colours, described elsewhere in this Magazine, which has no counter- 

 part in the Ulu Gopeng section. If therefore we assume the clay to 

 be schists like those at Ulu Gopeng weathered so as to lose all trace 

 of bedding we have to explain why alteration by the granite 

 produced such different results on the same material. The granite 



