CONTENTS. 



IX 



PAGE 



Chapter XVI. The Fire Clays and Fire-brick Industry, 31 1-333 



Properties of fire clays, 311 



Definition, 311 



Chemical composition, 311 



Effect of silica, 312 



Effect of titanium, 317 



Other properties, 321 



Mineral impurities, 322 



Uses of fire clays, 322 



History of the fire-brick industry, 323 



Method of manufacture, 324 



Tests of New Jersey fire brick, 326 



Chapter XVII. The Clay-mining Industry, .335-342 



Introductory statement, 335 



Middlesex county, 336 



No. 1 fire clay, 337 



No. 2 fire clay, 337 



Retort clays, 337 



Stoneware clay, 337 



Ball clay, 338 



Sagger clay, 338 



Wad clay, 338 



Terra-cotta clay, 338 



Pipe clay, 338 



Hollow-ware clay, 338 



Trenton area, 339 



Delaware river area, 339 



Woodmansie area, 339 



Methods of mining, 339 



Amount of clay mined in 1902, 340 



Shipments to other States, 341 



Directory of clay miners, 342 



PART IV.-THE ECONOMIC GEOLOGY OF THE NEW JERSEY 



CLAYS. 



Chapter XVIII. Economic Description of the Clay-bearing For- 

 mations, 343-366 



Post-Pleistocene and Pleistocene, 343 



Cohansey clays, 348 



Alloway clay, 351 



Asbury clay, 353 



Clay Marl IV, 356 



Clay Marl III, 357 



Clay Marl II, 357 



Clay Marl I, 360 



Raritan clays, 363 



Triassic shales, 365 



Hudson shales, 365 



