1888.] PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 121 



of the Siberiau nephrites, but presents certain peculiarities. The 

 grouudrnass has a like micro-granular and fibrous structure, but sections 

 cut at varying angles with the apparent schistosity show no such sep- 

 aration between the granular and fibrous parts as was observed in the 

 Siberian stone. These structures are shown in figs. 3 and 4, PI. i, 

 of tbeir paper. They think to distinguish between the Jarkand and 

 Siberian nephrites by their inclosures of foreign particles. In all Si- 

 berian nephrites the iron occurs in the form of limonite or chromite, 

 while in those of Jarkand it occurs wholly as magnetite and hematite. 

 These differences are shown by analysis. Another marked difference 

 lies in the irregular massive aggregates sometimes occurring iu sizes up 

 to 0.05 mra . These from their optical and cleavage properties are judged 

 to be diopside. A nephrite from Samarkand showed inclosures of a 

 similar nature. 



The distinction given in the resume by these authorities, between the 

 Siberian and Turkestan nephrites, are that the first named show a clear 

 microschistose structure with inclosed grains of chromite and limonite; 

 while the last named is massive, with very few inclosures of ferrugi- 

 nous granules, but in place of these characteristic inclusions of diop- 

 side or a closely related mineral. A nephrite from Pekin was found 

 to possess all the microscopic properties of that from Jarkand. The 

 microscopic examinations of Messrs Beck and Muschketow were in 

 all cases accompanied by chemical analyses, and the paper as a whole 

 forms a most important addition to the literature of the subject. 



Mr. Otto Schcetensack,* in a paper on the subject, describes a nephrite 

 from the Tienshau Mountains of a dark green color and specific gravity 

 of 2.98, which shows between crossed nicols a fine crystalline texture, 

 with many included asbestus-like fibers, giving extinction angles varying 

 from 12° tolG°. Earelyare seen concentric aggregates of fine bent fibers. 

 Strongly dichroic, yellowish brown and yellowish green granules are 

 supposed to be epidote. Another nephrite from Khoten in Bokhara, 

 with a specific gravity of 2.947 and of a violet-gray color, shows between 

 crossed nicols a confused, short fibrous texture, with the fibers but 

 slightly bent, through which are distributed large crystalline areas in 

 which the fibers are much more contracted. This is apparently the 

 same structure as shown in some Siberian nephrites by Beck and 

 Muschketow. 



Of jade objects from Mexico the National Museum has a large and 

 fine series, but nearly all the specimens are from the one State of Oaxaca. 

 The greater number of them consist of true jadeite ; but as jadeite from 

 the same region has been described by Damour, t a very exhaustive 

 review of the material did not seem to be necessary. A good series of 

 specific gravity determinations was, however, made by Dr. Hallock, and 



*Die Nephritoide des mineralogiscken u. d. ethnographiscli-pWiliistorischen Mu- 

 seums der Uuiversitiit Freiburg im Breislau. Inaug. Dis. Berlin, 1885. 

 t Bull Soc. Miu., iv, 157. 



