CATALOGUE OF GEMS AND PRECIOUS STONES. 31 



LIST OF SPECIMENS. 

 CEYLON. 



Step-brilliant, rectangular girdle; yellow-brown; 8.48 carats; 14 by 9 by 8 

 mm. Isaac Lea collection No. 555 



Step-brilliant, elliptical girdle; pale yellow; 0.43 carat; 5.5 by 5 by 3 mm. 

 Isaac Lea collection No. 556 



THE LEVANT. 



Step, rectangular girdle; dark green; 18.5 carats; 20 by 16 by 7 mm No. 554 



Step, rectangular girdle; yellow-green; 8.858 carats; 15 by 12 by 6 mm No. 553 



UNITED STATES. 



Arizona. 

 Navajo Indian Reservation: 



Brilliant, circular girdle; deep green; 3.93 carats; 10 by 7 mm No. 1181 



Brilliant, square girdle; dark green; 2.74 carats; 9 by 6 mm. Isaac Lea 

 collection No. 557 



New Mexico. 

 Fort Wingate, Bernalillo County: 



Brilliant, circular girdle; dark green; 1.65 carats; 8 by 6 mm No. 558 



Brilliant, circular girdle; dark green; 1.56 carats; 7.5 by 5.5 mm No. 560 



Brilliant, circular girdle; dark green; 1.48 carats; 8 by 5 mm No. 559 



Brilliant, circular girdle; dark green; 1.417 carats; 8 by 5 mm No. 562 



Brilliant, circular girdle; dark green; 1.226 carats; 7.5 by 5 mm No. 561 



Step-brilliant, rectangular girdle; green; 1.094 carats; 7 by 6 by 4 mm. No. 563 



Chrysoprase. — See under Chalcedony. 



Conch Shell. — See under Calcite and Aragonite. 



CORAL. 



Corals are composed of calcium carbonate and are formed as stony 

 secretions within the body of the coral polyp. Of the many varieties 

 known only those formed by the Corallium rubrum from the African 

 coast of the Mediterranean are utilized for gem purposes. The 

 material is dredged from a depth of 500 to 800 feet by means of metal 

 dragnets. The colors vary from deep red through pink to greenish, 

 brown, yellow, white, and black. The white, pink, and red varieties 

 are utilized chiefly in the form of necklaces and bracelets. 



LIST OF SPECIMENS. 



Bracelet, red No. 1515 



Small chain of beads, red No. 1516 



Two roses, red Nos. 1517, 1518 



Twenty- two spherical beads, white, 3 circular beads, pink; 4 rings, 5 leaf 

 shaped, and 36 small branching pieces, red. Gift of H. P. Petersen. 



Nos. 1843, 1844, 1845 



CORUNDUM. 



Varieties and synonyms. — Ruby, sapphire, oriental amethyst, 

 oriental emerald, and oriental topaz. 



Composition. — Aluminum sesquioxide, A1,0 3 : the aluminum may 

 be partially replaced by chromium, iron, titanium, etc., yielding 

 colored varieties. 

 4555—22 1 



