MARYLAND GEOLOGICAL SURVEY 213 



be dug. The stripping is done with a steam-shovel. Between the 

 kaolin and sand there is often a. layer of sandy, micaceous clay, more 

 or less mottled with limonite stains. This is sometimes sold for 

 making saggers. 



The kaolin pit is a long opening running about northwest and 

 southeast, with the washing plant near the latter end. 



Two grades of kaolin are recognized, the second having some iron 

 stains. Both grades are washed, but the lower quality is sometimes 

 sold in its crude form for fire-clay or sagger-clay. 



The method employed in washing the clay is not unlike that used 

 at other works and consists in first dumping the crude kaolin and 

 water on the sand-wheels. These, as is well known, remove 

 much of the sand, and the remainder which remains in suspension 

 together with the kaolin is washed along the troughing, where most 

 of the fine sand is dropped before the settling tanks are reached. 

 There are about 700 feet of troughing which is in 120-foot lengths. 

 There are 3 settling tanks, from which the kaolin, after settling, is 

 pumped into the filter press. Of these there are three, of Robinson 

 make. 



The sand which is separated is thrown away. . The kaolin is used 

 chiefly for paper manufacture. 



The washed product forms 30$ of the quantity mined. 



The pressed clay is dried on racks in the open air. 



It is probable that with the development of the kaolin field in 

 Cecil county additional washing plants will be erected. The works 

 are shown in Plate XVII, Tig. 2. 



The washed clay from the pit of the Maryland Clay Company 

 shows the following characteristics: There are considerable quanti- 

 ties of small mica scales, whose presence is undoubtedly shown by 

 the silica percentage found on analysis of the material as given below, 

 still the material, which is used chiefly in the manufacture of paper, 

 is very refractory, for there is not sufficient mica or undecomposed 

 feldspar present to act as a powerful flux. As is the case with most 

 kaolins the tensile strength of the material is very low and, therefore, 

 no briquettes were made. Some bricklets of the material yielded the 



