72 



may be separated in the quarry in large regular masses— and hence 

 for slabs, pavements, and general building use, may be advantage- 

 ously employed. At the Buckingham iron works, it has been used 

 in the furnace stack, and has been found to answer well. 



The silicious micaceous slate occurs a little west of the former, 

 and has a sensible dip to the east, though almost vertical. This 

 rock is of a light yellowish brown colour, contains a small propor- 

 tion of mica, some felspar, and a large amount of silcx, apparently 

 in grains ; and in fact, at first view, presents the aspect of some 

 sandstones, though probably more nearly allied to the mica slates 

 than any other known rocks. It may be quarried out in long rect- 

 angular prisms, with surfaces nearly as smooth as if formed by the 

 chisel, and from its hardness and durability under exposure, is to be 

 looked upon as a valuable rock. When intensely heated, it becomes 

 glazed on the surface, and is used for the floor of the iron furnace at 

 New Canton. 



Associated with these beds, is one containing crystallized garnets 

 in great numbers, and sometimes of exceeding beauty. This rock 

 often contains much chlorite, and presents a general greenish aspect. 

 Large quantities of it have been quarried in building the dam at New 

 Canton, and a portion peculiarly abundant in the garnets, has re- 

 cently been introduced in the furnace as an auxiliary flux. The 

 large proportion of lime contained in the garnets fitting the rock pe- 

 culiarly for this purpose, while at the same time it yields a conside- 

 rable amount of iron. 



The whetstone beds which occur among the silicious and other 

 slates, also furnish a material of high value. The texture of this 

 stone is exceedingly close and fine ; it possesses a proper degree of 

 hardness and great permanency under atmospheric exposure. Its 

 apparently fibrous structure, and the long shape of the masses which 

 are separated in the quarry, give it the appearance of a log of wood, 

 partially decayed. The trial of its qualities as a whetstone, made 

 in Fluvanna, Rockbridge, and the neighbouring counties, amply de- 

 monstrate its excellence for this purpose, and in some instances, ex- 

 perienced mechanics have evinced their sense of its superior value 

 by laying aside the Turkey oilstone, and substituting this in its 

 place. 



One of the most interesting and valuable of the slaty rocks of this 

 region, is the roofing slate which occurs in a thick bed west of the 

 strata which have just been described. This makes its appearance 



