L16 



NEPHRITE AND JADEITE. 



Of these the last two were collected by the Signal Service expedition 

 commanded by Lieut. P. II. Kay; the others were received from Mr, 

 E. VV. Nelson. For each specimen the specific gravity was carefully 

 determined by Dr. William Hallock, of the U". S. Geological Survey. 

 The general description of the material may be summarized thus: 



13415. Yellowish-green, mottled, sp. gr. 2.989. 



13440. Siskin-green, translucent, uniform sp. gr. :5.00G. 



14606. Olive-green, sp. gr. 2.988. 



14920. Olive-green, mottled, sp. gr. 2.928. 



1 1921. Olive green, mottled, darker, sp. gr. 2.921. 



14922. Superficially black, sp. gr. 2.963. 



63715. Siskin-green, translucent, sp. gr. 3.002. 



63733. Blackish green, mottled and laminated, sp. gr. 3.010. 



63762. Olive-green, mottled and laminated, sp. gr. 2.975, 

 2. Olive-green, translucent, sp. gr. 2.978. 



89658. Nearly black superficially, sp. gr. 2.922. 



Of these. Nos. 43415,43440, G3733, aud 89658 were selected for analy- 

 sis and microscopic stud}'. The following table gives the results of the 

 analyses : 



Ignition 1.91 



Silica -5G.01 



Alumina.... 1. 98 



Ferrous oxide 6. 34 



Maganoua oxide trace. 



Lime | 12.54 



Magnesia 21. 54 



43415 43410 63733 89658 



100. 35 



1.42 



56.12 



.63 



7.45 



trace. 

 12. 72 

 20. 92 



99.26 



2.03 



56.08 



1.01 



7.67 



trace. 



13. 35 



19.96 



100. 10 



2.06 



57.11 



2.57 



5.15 



trace. 

 11.54 

 21.38 



99.81 



1 n each case the ferrous oxide represents the total iron. Ferric oxide 

 was not discriminated, nor were alkalies looked for. So far, then, the 

 analyses are imperfect. 



In addition to the above-named implements, another object of sup- 

 posed jade was investigated. It was a rlaker (Ko. 89624) from Point 

 I ia now, of dull bluish green color, conchoidal fracture, considerable 

 translucency, and specific gravity 2.654. These data, together with a 

 partial analysis, identify the specimen as quartz. It contained 97.79 

 per cent, of silica. 



Before going on with the discussion of the microscopic character of 

 the jades another series of specimens remains to be noticed. As re- 

 gards origin, some early writers have attributed the Alaskan nephrite 

 to Siberian sources, but of late years it has been generally ascribed to 

 a home locality. Native reports pointed to a source known as the Jade 

 Mountains, north of the Kowak River, about 150 miles above its mouth ; 

 and alter several attempts the spot has been actually visited by Lieut. 

 (1. .M. Stoney. He collected specimens of jade in situ, and a number of 

 samples were submitted to us for examination. They may be described 

 as follows : 



A. Greenish gray, splintery, lamellar in structure, 



