,24 NEPHRITE AND JADEITE. 



The second jade, No. LL5213, is, like the last, an aggregate of imper- 

 fectly outlined crystals. CTnder the microscope the texture is found to 

 be very uneven; portions of the slide showing aggregates of extremely 

 small and ill-defined particles which permit of no satisfactory measure- 

 ments or determinations, sometimes slightly fibrous or scale-like, and 

 sometimes granular, while other portions show distinct crystalline 

 forms of all sizes up to 1 millimeter in diameter and which show the 

 cleavage and optical properties of a mouoclinic pyroxene. The clear, 

 colorless, mica-like mineral also occurs here. The rock otherwise dif- 

 fers in no essential particular from a .jadeite from China, samples of 

 which we have here, received from Dr. A. 1). M eyer (28820). 



With Central American jade objects the Museum is well supplied. 

 A few only are from Nicaragua and Guatemala ; the finest are all Costa 

 Rican. Here. too. jadeite is the dominating mineral species; although 

 with the true jades are many articles of softer green stones, and oc- 

 casionally an object of quartz or chalcedony. To Dr. Hallock's series 

 of specific gravity determinations we may properly add a number of 

 earlier values obtained several years ago by the late G. W. Hawes and 

 by Mr. F. W.Taylor, and not hitherto published. The specimens ex- 

 amined are described below, following the order of their density: 



No. 5993 J. Polished ornament, Sardinal, Costa Rica. Deep olive-green, not dis- 

 tinctly granular, specific gravity 3.344, Hallock. 



No. 59908. Polished ornament, Sardinal. Pale green with whitish flecks, translu- 

 cent, Blightly granular, specific gravity 3.332, Hallock. 



No. -,'-'.i?7. Elahorate (•.living, Nicoya, Costa Rica. Dark, rich green, translucent, 

 granular, specific gravity 3.33, Hawes. 



No. 31906. Polished tnbe, Guatemala. Light, grayish green, granular, specific grav- 

 ity 3.33, Hawes. 



No. 28990. Fragment, Sardinal. Light green, very granular, specific gravity 3.33, 

 Hawes. 



No. 59907. Ornament, Sardinal. Mineral like No. 28977, specific gravity 3.326) 

 Hallock. 



No. 59947. Ornament, Jesus Maria, Costa Rica, Blackish green, mottled, granular, 

 specific gravity 3.32, Taylor. 



No. 59927. Fragment, Sardinal. Pale green, translucent, specific gravity 3.32, Clarke. 

 No. 28992. Fragment, Cnlebra, Costa Rica. Mineral, like No. 28990, slightly darker. 

 specific gravity 3. -27, Clarke. 



No. 28991. Hatchet, Liberia, Costa Rica. Grayish greeu, finely granular, specific 

 gravity, 3.26, Hawes. 



No. 10452. Large ornament Ometepec Island, Lake Nicaragua. Varying shades of 

 green and grayish green, very finely granular, specific gravity 3.26, Hawes. 



No. 59968. Small ornament, Nicoya. Dark greeu, not distinctly granular, specific 

 gravity 3.11, Taylor. 



No. 59917. Small ornament, Sardinal. Bright green, granular, specific gravity 3.01, 

 Taj lor. 



No. 59857. Small ornament. Las Huacas, Costa Rica. Green and gray blotches. 

 coarsely granular, specific gravity 2.956, Hallock, 



No. 28 -7. Ornament, Liberia. Greenish gray, granular, specific gravity' 2.87, 

 Hawes. 



No. 60048. Fragment, Rio de Buena Vista, Costa Rica. Green, translucent, specific 

 gravity 2.71, Clarke. 



