LIST OF ILLUSTRATIONS. 



PLATES. 



Facing page. 



1. Portrait of Dr. Isaac Lea Frontispiece. 



2. Portrait of Dr. Leander T. Chamberlain 2 



3. Mineral Hall, U. S. National Museum 8 



4. Benitoite mine, near San Benito Peak, California 12 



5. Alluvial sand carrying chrysolite. Navajo Indian Reservation, Arizona 30 



6. Sapphire mine, Fergus County, Montana 35 



7. Semi-precious stones 43 



Fig. 1, Lapis-lazuli; 2, chlorastrolite; 3, malachite; 4, 5, silicitied 

 wood; 6, thomsonite; 7, crocidolite; 8, bloodstone; 9, amazonstone; 10, 

 jasper; 11, unakite. 



8. Open cut emerald mine, now abandoned, near Shelby, North Carolina 54 



9. Monarch opal mine, Virgin Valley, Humboldt County, Nevada 73 



10. Tourmaline and feldspar mine, Auburn, Maine 107 



11. Turquoise mine, near Cerrillos, New Mexico 113 



12. Variscite, turquoise, chrysoprase, and jade 115 



Figs. 1, 2, 3, 4, 6, 7, 8, variscite; 5, chrysoprase; 9, 11, jade; 10, 12, 13, 

 14, turquoise. 



13. Variscite in matrix, Variscite mine, near Lucin, Utah 121 



14. South African diamond mine 134 



TEXT FIGURES. 



Page. 



1 . Shell cameo 19 



2. Banded Agate 20 



3. Moss Agates 26 



4. Corundum crystals 32 



5. Diamond crystals, enlarged. From Gardner F. Williams Collection 44 



6. Garnets, in matrix 56 



7. Malachite and azurite 71 



8. Baroque pearls 77 



9. Large amethystine quartz 82 



10. Quartz containing rutile needles 84 



11. Staurolites, or Fairy stones 102 



12. Topaz crystal in matrix 104 



13. Chinese carving in turquoise 114 



14. Moss agates in rough and cut forms 121 



15. Lizard carved in opal on limonite 132 



16. The Brilliant 142 



17. The Double Brilliant 143 



18. The Half Brilliant 143 



19. The Trap Brilliant 143 



20. The Portuguese Cut 144 



21. The Star Cut 144 



22. The Rose Cut 144 



23. Trap Cut 145 



24. The Step Brilliant Cut 145 



25. Table Cut 145 



26. The Cabochon Cut 146 



VIII 



