CATALOGUE OF GEMS AND PRECIOUS STONES. 131 



LABRADORITE. 



LIST OP SPECIMENS. 



Medallion of a knight's head; gray, blue, green, etc., in play of colors; 10.5 



by 7.5 cm. Labrador No. 1750 



Small monumental shaped object; gray; 10 cm. high. Labrador No. 1749 



LEPIDOLITE. 



A lithia mica of a pink color and sometimes sufficiently compact 

 to be carved into small ornaments. It occurs associated with gem 

 minerals (tourmaline) in the pegmatite quarries of Maine, California, 

 and elsewhere. 



LIST OP SPECIMENS. 



Ash tray; rectangular; violet-red; 9 by 4.7 by 1.3 cm. Rozena, Moravia. 

 Gift of C. S. Bement No. 1748 



MALACHITE. 



LIST OF SPECIMENS. 



Cube with truncated edges; green; 5 cm. Morenci, Arizona No. 1696 



Composite slab; green; 11 by 8.5 cm. Ural Mountains No. 1697 



MARBLE, CALCITE, and ARAGONITE. 



Calcium carbonate occurs in nature under a great variety of forms, 

 usually included under the mineralogical names of calcite and arago- 

 nite, or occurring in large rock-like masses as limestone and marble. 

 The last named forms are used extensively in building and the finer 

 grades (marble) for decorative work, statuary, and ornaments. 

 Travertine, cave marble, and onyx marble are the names given to 

 deposits on the surface or in caves and crevices in limestone, from 

 water solutions. These are sometimes of exceptional beauty. The 

 so-called oriental alabaster used by the ancient Egyptians was a 

 travertine found in caves and fissures in the Eocene limestone of 

 Egypt. Lumachelle is a name given to a variety in which the 

 included shell fragments still retain their original nacreous or pearly 

 luster. Other varietal names are given according to origin, color, and 

 structure. These are to be found in the collection of building and 

 ornamental stones. (See also under coral and pearl, pp. 31 and 77.) 



LIST OP SPECIMENS. 



Sphere of onyx marble; green- yellow; 9 cm. diameter. Big Buck Creek, 



Arizona No. 1766 



Sphere of travertine; pale yellow; 7.8 cm. diameter. Yavapai County, 



Arizona No. 1765 



Carving of a dragon on black limestone. Japan No. 1689 



Sphere of marble; brown and gray; 8 cm. diameter. Japan No. 1770 



Paper knife of onyx; 19.2 cm. long. Puebla, Mexico No. 1715 



4555—22 11 



