322 BULLETIN 131, UNITED STATES NATIONAL MUSEUM 



Per cent 



Lanthana (La 2 3 ), Praesia (Pr 2 3 ), Neodymia (Nd 2 3 ) 5. 52 



Alumina (A1 2 3 ), soda (Na 2 0) and potash (K 2 0) Trace. 



Water (H 2 0) • 48 



Total 99. 12 



A second mineral occurring as dark bottle green inclusions in the 

 gadolinite was also analyzed with the following results: 



Analysis of mineral included in gadolinite 



(G. Chernik (Tschernick), analyst) 



Per cent 



Yttria (Yt 2 3 ) 51. 94 



Ceria (Ce 2 3 ) 14. 49 



Silica (Si0 2 ) 26. 08 



Beryllia (BeO) • 54 



Thoria (Th0 2 ) 2. 77 



Ferrous iron (FeO) 1- 58 



Lime (CaO) • 62 



Magnesia (MgO), Manganese (MnO), potash (K 2 0), soda (Na 2 0) Trace. 



Water (H 2 0) • 97 



Total 98.99 



The specific gravity of the latter mineral is 4.536. Chernik states 

 that it is a variety of gadolinite with the formula 16(Y 2 3 .2Si0 2 ). 

 2 (2 Ce 2 3 .3S10 2 ) . ThSi0 4 .Be 2 Si0 4 .2FeO. Ca0.5H 2 0. 



Doelter 51 gives as the formula for the gadolinite of the first 



analysis: 



3(Be.Fe)O.Y 2 O 3 .2SiO 2 = Be 2 FeY 2 Si 2 O 10 



and for the mineral of the second analysis : 



II III IV 



R 5 R 40 RSi 4 oO H 7.5H 2 



with RO : R 2 3 : Si0 2 as 0.3 : 1 : 2. Doelter states that this can 

 not be gadolinite and is either a mixture or a new mineral. 



ZOISITE (406) 



Calcium-aluminium silicate, Orthorhombic. 



4Ca0.3Al 2 3 .6Si0 2 .H 2 0. 



Zoisite, both the ordinary whitish-colored material and the pink 

 variety which is called thulite, have been identified microscopically 

 in the Seven Devils district in Adams County and a single lot of 

 specimens of zoisite from the Avery quadrangle in Shoshone County 

 has been examined. 



ADAMS COUNTY 



Zoisite occurs in the Seven Devils district as a contact mineral as 

 described by Livingston and Laney. 52 At some places, notably the 



«' C. Doelter. Handbuch der Mineralchem., vol. 2, p. 179, 1915. 



« 2 D. C. Livingston and F. B. Laney. Idaho Bur. Mines and Qeol., Bull. 1, pp. 48, 62, etc., 1920 



