1 82 CLAYS AND CLAY INDUSTRY. 



of the feldspar would be hard enough to resist much wear, and be 

 finally deposited in a firm, condition. Part may have already been 

 completely kaolinized and formed clay lumps, in which suban- 

 gular quartz grains were already imbedded or became imbedded 

 during transportation. The clay lumps would of course have been 

 greatly diminished in size by transportation even a short distance 

 only, but may still not have been completely worn away. But 

 whatever may be the difficulties in determining the exact method 

 ini all details by which this material was formed, its ultimate 

 derivation from a quartz-feldspar rock, and its, deposition in its 

 present position by water cannot be questioned. 



The "feldspar" is used chiefly in the manufacture of fire brick, 

 but it is not dug so much as, formerly. The main workings at 

 present are the banks of Valentine (40), Maurer (41), Staten 

 Island Clay Company (32), and Remy (242), all north of the 

 Raritan river. A few pits have been dug near the shore northwest 

 of South Amboy, but they are not worked at present. Since the 

 "feldspar" occurs as lenses, and not as a continuous bed, it is 

 impossible to map it definitely. Its occurrence, however, is limited 

 to> the zone between; the black clay of the Woodbridge bed and 

 South Amboy fire clay, so that its general horizon can be definitely 

 fixed. 



The so-called "kaolin" is not in any sense of the term a kaolin, 

 although always so> named in this district. It "is a micaceous 

 sand, consisting- of very fine-grained, white quartz sand, mixed 

 with a small and varying percentage of white mica, in small flakes 

 or scales, and a very little white clay. The mica is, however, con- 

 spicuous, and gives the mass a glistening appearance and a some- 

 what soft and soapy feel, but the sand is largely in excess, consti- 

 tuting - from 60 to 90 per cent, of the mass in the more clayey and 

 micaceous specimens." 



the; woodbridge clay. 



General distribution. — Beneath the "Feldspar-Kaolin" sands, 

 there occurs the Woodbridge clay bed, the most important and 

 most widelv worked of all the subdivisions of the Raritan forma- 



