484 CLAYS AND CLAY INDUSTRY. 



viz., an upper bluish-white, mottled clay, which is rather sandy 

 in its upper layers, and passes upwards into the gravelly over- 

 burden. This upper clay, as exposed, ranges from 3 to 4 feet in 

 thickness. The lower bed, which was bored into for a distance 

 of 5 feet, consists of red and chocolate layers which may contain 

 pebbly streaks. The total thickness of the clay is said to be as- 

 much as 24 feet, and the overburden is about 4 feet thick. The 

 upper clay (Lab. No. 666), when examined in the laboratory, was 

 seen to> be a gray, sandy, slow-slaking clay, with practically no> 

 mica scales. It burned buff at cones 3, 5 and 8, with fire shrink- 

 age of 4, 5 and 6 per cent., respectively, and became steel-hard at 

 cone 5. When made up into dry-press tiles its fire shrinkage at 

 cone 5 was 2.6 per cent., and at cone 10, 13.3 per cent., the per- 

 centages of absorption being respectively 16.36 per cent, and 6.40 

 per cent. The color of the former was buff and of the latter light 

 gray. It was analyzed with the following result : 



Chemical analysis of a clay from Mayetta. 



Silica ( SiO->) , 76:40 



Alumina ( ALO s ) . 13-29 



Ferric oxide (Fe20 3 ), 0.82 ■ 



Lime ( CaO ) , 0.95 



Magnesia (MgO), 0.61 



Alkalies (Na.O, K,0), 1.80 



Water on ignition, S- 10 



Total, 98.97 



Total fluxes, 418 



The low percentage of ferric oxide explains its buff-burning 

 character, while the high percentage of total fluxes and silica show 

 that it is not a fire clay. 



The lower bed burned buff, also, and became steel-hard at cone 

 1, with fire shrinkage of 4.7 per cent, and an absorption of 10.52 

 per cent. At cone 5 its fire shrinkage was 8 per cent, and absorp^ 

 tion 3.06 per cent. Its air shrinkage was 5.3 per cent. It is diffi- 

 cult to see how the local brickyard made red brick out of this clay, 

 as was claimed. 



An additional deposit of clay is said to exist on the adjoining- 

 property, belonging to the Hazleton estate. 



