LIST OF ILLUSTRATIONS. 



PLATES. 



Facing page. 



1. Banded nodules of azurite and malachite, Morenci, Arizona. Specimen 



No. 48567, U.S.N.M 490 



2. Crocidolite in ([uartz, Griqualand West, South Africa. Specimen No. 4710.'i, 



U.S.N.M '. 500 



3. Amazonstone, Pikes Peak, Colorado. Specimen No. 81813, U.S.N.M 514 



4. Opalized wood, Clover Creek, Lincoln County, Idaho. Specimen No. 



82584, U. S. N. M .' 518 



5. Crystal.- of (inartz, Dauphiny, France. Sjjecimen No. 82218, U.S.N.M 522 



(i. Carnelian ajiate, Uruguay. Specimen No. 61770, U.S.N.M 524 



7. Kutile in (juartz (Venus' Hair Stone), Alexander County, North Carolina. 



Specimen No. 47620, U.S.N.M 526 



8. Topaz with smoky quartz. Specimen No. 81242, U.S.N.M 530 



9. Siberian topaz. Specimen No. 8 1244, U.S.N.M 532 



TEXT FIGUEES. 



Page 



1 . Diagram t( ) illustrate refraction 483 



2. Diagram to illustrate double refraction 483 



3. Nich( )ls()n hydrometer 485 



4. Emerald crystal. Stony Point, Alexander County, North Carolina; weight, 



8| ounces. Specimen No. 83730, U.S.N.M 491 



5. Corundum crystals, Ceylon. Specimen No. 81441, U.S.N.M 498 



6. Diamond crystals, Kimberly Mines, South Africa. Specimen No. 84799, 



U.S. N.M 504 



7. Garnet crystal and pebbles of pyrope. Specimen No. 82575, U.S.N.M 510 



8. Agate, Brazil. Specimen No. 44948, U.S.N.M 521 



9. Agatize(lwood,Chalcedony Park, Arizona. Specimen No. 82485, U.S.N.M. 522i 



10. Amethyst crystals. Upper Providence, I'ennsvlvania. Specimen No. 83676, 



U.S.N.M ■ 523 



11. Moss agate, Sheridan, Kansas. Specimen No. 49261, U.S.N.M 525 



12. Spinel crystals, Kandy, Ceylon. Specimen No. 49163, U.S.N.M 528 



13. Topaz pebbles (gouttes d'eau), Mitchell River, New South Wales. Speci- 



men No. 83782, U.S.N.M .' 531 



14. The brilliant: <i and /^ manner in which the brilliant is derived from the 



fundamental form; c, <I, and e, top, side, and back view of brilliant with 

 58 facets; /, y, and //, top, side, and back view of modified l)rilliant with 

 66 facets 548 



15. The double brilliant: top {a), side (h), and back (c) view 549 



16. The half brilliant: top {a) and side {h) view of half brilliant. In c the 



top is cut in the form of a star, then called English single cut 549 



479 



