164 REPORT OF NATIONAL MUSEUM, 1899. 



Facing page. 



24. Map showing the developed coal fields of the United States. From 



the Report of the P^leventh Census 426 



25. Map showing areas where bitumen occurs in the United States and 



Canada. From the Report of the Tenth Census 429 



26. Plan of Pitch Lake, Trinidad. After S. F. Peckham 442 



27. Nodule of gum copal from Congo River region, Africa. Specimen No. 



62717, U.S.N. M 457 



28. Microsection of mica schist used in making whetstone. Fig. 1, cut 



across foliation. Fig. 2, cut parallel to foliation 467 



29. View of Novaculite Quarry, Arkansas. After Griswold, Annual Report of 



the Geological Survey of Arkansas, III, 1890 468 



30. Microsections showing the appearance of (1) Arkansas Novaculite and (2) 



Ratisbon razor hone. The dark l)odies in (2) are garnets 470 



TEXT FIGURES. 



Page. 



1. Block of limestone with alternating bands of sulphur. Sicily, Italy. Spec- 



imen No. 60932, U.S.N.M 179 



2. Cluster of halite crystals, Stassfurt, Germany. Specimen No. 40222, 



U.S.N.M 195 



3. Geological section of Petite Anse Island, Louisiana 201 



4. Cluster of sylvite crystals, Stassfurt, Germany. Specimen No. 40223, 



U.S.N.M 203 



5. Pisolitic bauxite. Bartow County, Georgia. Specimen No. 63335, U.S.N.M. 229 



6. Map showing geological relations of Georgia and Alabama 1)auxite 



deposits. After C. W. Hayes 235 



7. Section showing relation of bauxite to mantle of residual clay in (ieorgia. 



After C. W. Hayes 236 



8. Section across paint mine at Lehigh Gap, Pennsylvania. After C. E. Hesse. 242 



9. Section of mica veins in Yancey County, North Carolina. After W. C. 



Kerr 288 



10. Asbestos fibers. After G. P. Merrill, Proceedings of the U. S. National 



Museum, XVIII, p. 283 297 



11. Serpentine asbestos in massive serpentine. Specimen No. 72836 302 



12. Map of Nitrate region, Chile. After Fuchs and De Launay 393 



13. Section through Sulphur Mountain, California. After S. F. Peckham 432 



