322 Penfield and Sperry — Mineralogioal Notes. 



frequently much shorter than represented in the illustration. 

 Many of the crystals are of considerable size, measuring over 

 one-half inch in diameter and one inch in length. The x faces 

 on the larger crystals are always dull and rough and the pris- 

 matic faces vertically striated. 



3. Monazite from Alexander Co., JV. C. 



Crystals of this mineral, from a locality about three miles 

 east of the Emerald and Hiddenite Mine, were first brought 

 to notice and described by Mr. ¥m, E. Hidden,* who sent us 

 several grams of very pure transparent crystals for chemical 

 examination. It seemed especially desirable to have ah analy- 

 sis of such a pure, crystallized variety, owing to the fact that 

 most analyses of monazite show a greater or less percentage of 

 Th0 2 , and the conflicting views relative to its relation to the 

 mineral; i. e., that it belongs in the composition of the min- 

 eral, although the oxide Th0 2 has no chemical relation to the 

 Ce 2 3 , La 2 ? and Di 2 3 , or that it is present together with 

 Si0 2 and H 2 as an impurity of thorite, ThSi0 4 , H 2 0. This 

 latter view was advanced by one of us in a former paper,f be- 

 ing substantiated by analytical results and microscopic examin- 

 ation, but the former view is still held by many and is especially 

 advocated by C. W. Blomstrand, who has recently published a 

 detailed paper X on the subject. 



The chemical analysis was made with great care by both of 

 us, according to the method described in the previous paper. 

 The specific gravity, taken with precision on a chemical 

 balance, was found to be 5 '203. The analysis yielded 



Sperry. Penfield. Mean. 



P 2 5 29-57 2895 29-19 29'57 .29-32 



Mixed oxides 71-91 72-37 72-25 72-18 



Si0 2 -24 '47 -32 



Ignition -17 -17 



The determination of Th0 2 and Ce0 2 in the mixed oxides and 

 calculation of CeO, to Ce 2 3 gave as the complete analysis : 



Katio. 

 •207 



-f- 328 -210 



•005 

 •005 



100*15 



The amount of thoria is very slight, really not greater than 

 the Si0 2 as can be seen by the ratio ThO, : Si0 2 = 1 : 1, al- 



* This Journal, III, xxxii, 207. f This Journal, III, xxiv, 250. 



% Geol. For. Forh., ix, p. 160, 1887. 



P 2 5 



29-32 



Ce 2 3 



3726 



(La, Di) 2 3 



31-60 



Th0 2 



1-48 



Si0 2 



•32 



Ign. 



•17 



