NEIGHBOURHOOD OF CORK. 87 



Where this rock is disposed to present any va- 

 riety of colour, it is in general greasy to the feel, 

 and likewise contains steatite. 



Subordinate to the rock which we have now de- 

 scribed, occur large masses of Slate-clay. It is 

 seldom found as a regular bed of any extent ; and, 

 at the line of junction, it coalesces with the preced- 

 ing rock. It is readily distinguished, however, 

 from that rock, by its colour and fracture. It is 

 bluish-grey, with a tinge of green or black. In the 

 finer kinds, the laminated structure cannot be per- 

 ceived, and the fracture is even, inclining to large 

 conchoidal. It is dull, — sometimes glimmering from 

 intermixed scales of mica, — fragments indetermi- 

 nately angular, rather sharp-edged, — opaqtie, — soft 

 in a slight degree, — streak dull, and light coloured, 

 jj — adheres feebly to the tongue, — easily frangible, — 

 and feels somewhat meagre. This variety is some- 

 times used as a whetstone for the coarser kinds of 

 cutlery. 



In many instances, this rock becomes fine earthy 

 in its fracture ; glimmering in its lustre ; consider- 

 ably harder ; and the fragments more blunt-edged. 

 Some varieties of this sort bear a close resemblance 

 to those floetz rocks which are intermediate between 

 sandstone and slate-clay. 



Subordinate likewise to the brownstone, already 

 described, is a rock which may be called Grey-wacke, 

 although destitute of many of the important cha- 

 racters of that rock. It exhibits two very distinct 

 varieties. 



