122 GEOLOGICAL SURVEY OF ALABAMA. 



of fine quality, gives hopes of yet finding it equally good, at 

 other places where the same formation is exposed. 



Whether any of this bed contains the proper proportion 

 of silica and alumina to make fire proof brick, is not yet 

 known. Some tests Lave been made, from a few places, 

 without giving satisfaction, but these have not been suffi- 

 ciently numerous to settle the question adversely. 



HONE STONE. 



Between the bed of halloyeite clay and the Black Shale, 

 generally close to the latter, there often exists a bed of very 

 fine grit rock. Some of it is soft, and suitable for hone 

 stones,*or for the finest edged tools or instruments. Other 

 portions harder and firmer, suitable for oil stones. Mech- 

 anics who have used these oil stones concur in regarding 

 them as superior to any found in the market. Some of the 

 stones had been accidentally found and used as whetstones 

 and oil stones during the last forty years, but the position 

 of the bed from whence they came was only discovered dur- 

 ing the progress of this survey. It is mostly of a light yel- 

 low color, softer and of finer grain than novaculite. Has a 

 finer texture and sharper grain than the Wachita oil stone. 

 It will become better known in the future. Its position is 

 on the western top or slope of Red Mountain the very 

 top member of the Lower Siliceous formation, just above 

 the Black Shale. 



BUILDING STONE. 



Among the upper members of the Clinton are two ledges 

 of sandstone, which in many places afford excellent building 

 rock. One is a ledge of flaggy sandstone, highly fissile, with 

 smooth faces. It may be split into any desired thickness. 

 And wherever it is solid enough for use, it is the most con- 

 veniently utilized building rock this region affords. Its 

 smooth faces which are perfect planes, and its uniform 

 thickness, make it very desirable for strong, solid work. 

 This kind of rock is only found at a few places, this ledge 

 being generally shaly. 



