



SKY. MINERALS. 41.5 



in some places passing gradually into that substance. 

 The visible edge is very irregular, the bed being inter- 

 rupted and split in many places by intruding laminee 

 of gneiss, while it sometimes also contracts to the breadth 

 of a few inches and again expands to one of as many feet. 



In general the rock presents a confused crystallization 

 of pale green actinolite, the crystals being commonly 

 minute and much entangled together. In a few instances 

 only its texture is larger, the crystals being wider, longer, 

 and placed in more parallel order, so as to give a longi- 

 tudinal flat platy fracture. It does not any where present 

 the fine fibrous, granular, or minute schistose texture 

 that is seen in the rock of Glen Elg, nor does talc 

 occur among it as in that place. The specimens that 

 are to be procured are therefore comparatively de- 

 ficient both in beauty and variety. Its passage into 

 hornblende schist appears sometimes to arise from a 

 gradual change in the colour and appearance of the 

 mineral, but most commonly takes place by an inter- 

 mixture of common black hornblende. Not unfrequently 

 a compound of this latter mineral, black mica, and ac- 

 tinolite, is found intermixed in the bed. The north-east 

 direction of the gneiss has already been pointed out, 

 and it is preserved in the bearing of this rock. It is 

 probably a prolongation of the well known bed of Glen 

 Elg, with which it coincides in position and direction, 

 as nearly as can be ascertained from the nature of the 

 mass. The prolonged rectilinear course of the gneiss 

 is thus confirmed, as well as the persistence of the beds 

 that enter into it : it may hereafter be an object of 

 curiosity to geologists to trace it still further north- 

 eastward from Eilan reoch : I attempted to pursue it 

 in the opposite direction from Camuscross but without 

 success. 



It is unnecessary to enter into further details respecting 

 the serpentine and the steatitical substances that accom- 

 pany the white marble, but I may mention, that, in the 

 i 



