[20 Nephrite and jadeite\ 



oepbrite in thatthe latter has its fibers finer and grouped in long 

 bunches, or in spreading tufts, as shown in our fig. -'i. Such, however, 

 may be mere local variations; and a more weighty distinction is based 

 upon the presence of inclosures of foreign matter in the Siberian 

 nephrite which arc quite lacking in the specimens from Alaska. The 

 analysis given by Dr. Meyer in this paper, although differing somewhat 

 from that of our scries, is sufficient to insure identity of material. 



Beck and Muschketow* describe the Kitoj River nephrite as dark 

 leek-green in color and of a lamellar structure. 



Sections cul parallel and at right angles with the lamination show 

 in the one case a prevailing confused fibrous and parall 1 fibrous (" ver- 

 worren-faseriges u. parallel fasciites") structure, and in the other a 

 microgranular and lamellar structure. Under a power of ninety-five 

 diameters and in ordinary light the section is traversed by clear colored 

 veins, which stand out boldly from the surface when the nicols are 

 crossed. These arc bordered by extremely fine fibers arranged both 

 parallel and at right angles with the veins, and show by their aggregate 

 polarization and optical behavior that they are asbestus. This struct- 

 ure is shown only in sections cut parallel with the lamination. The 

 Belaja River nephrite is described by the same author as showing un- 

 der the microscope a confused fibrous aggregate of extremely line 

 needles of various sizes, the larger some 0.0043 mm in thickness, and, with 

 a length many times greater, rarely a thickness of 0.0I mm is attained. 

 The libers arc extraordinarily confused and without the slightest regu- 

 larity in their arrangement, though in some cases au approximately 

 parallel arrangement occurs which gives rise to a pseudo-microfluidal 

 structure. .More commonly the fibers are found in tufts, radiating 

 from a commmon point, " StraMenartig." In consequence of the homo- 

 geneity of the aggregate it is assumed that the fibers belong all to the 

 same mineral species. Inclusions are abundant. Limonite is the most 

 common, occurring as small black points, and often staining the ad- 

 jacent needles a brown color. This coloring matter sometimes segre- 

 gates into veins of sufficient size to be apparent to the unaided eye. 

 Other dark inclosures are believed to be chromite. As in the last case, 

 sections at right angles to the lamination show a less pronounced 

 fibrous structure, but are rather microgranular. Stillanother nephrite 

 from the Bnstraja River has the fibers so extremely small that a great 

 number could be seen (when magnified five hundred diameters) grouped 

 in a space 0.0043 mm in breadth. These asbestus-like fibers are regarded 

 as secondary, as are also small colorless sections with which they are 

 sometimes associated, and which from their optical behavior are sup- 

 posed to beserpentine. A nephrite from the Caucasus has similarprop 

 cities. One from the Jarkand Valley in Turkestan differs from the 

 last in carrying a considerable number of magnetite inclosures which 

 are visible to the naked eye. Its microstructure greatly resembles that 



•I'. Nophril 11. seine Lagerstatten. Verhand. .In- Kaiserlichen Min. Gesell. zu St. 

 Petersburg : u series, \\ in. 



