40 JOURNAIy OF THE 



(1) to (4) inclusive are from peg-matite veins of southern Norway, 

 by C. W. Blonistrand. (5) From I^ake Ilmen, Russia, by R. Her- 

 mann. (6 From Arendal, Sweden, by C. F. Rammelsberg-. (7) From 

 Ottawa County, Quebec, by F. A. Genth. (8) From Burke County, 

 N. C, by S. Iv. Penfield. 



Penfield" deduces the molecular formula: 



(Ce,La,Di),03 : P.O^ =1:1; 



THO2 ' SiOs =1:1. 



The former corresponds to the normal phosphate 

 of the cerium metals (RgPsOj; the latter corresponds 

 to the normal thorium silicate, which, in combination 

 with a small percentag-e of water, makes the mineral 

 thorite or orang-ite (ThSi04.H2 0). He concludes, 

 therefore, that monazite is essentially a normal phos- 

 phate of the cerium metals, in which thorium silicate is 

 present in varying- proportions as an impurity in the 

 form of the mineral thorite or orangite. 



Dunningtont had soniewhat previously come to the 

 same conclusion. Rammelsberg'si formula of thorium 

 free monazite from Arendal, Norway, was RgPgOg = 

 (Ce, La, Di)2P2 08, thus ag-reeing- with Penfield. 



Blomstrand,§ from his analysis of Norwegian and 

 Siberian monazite concludes that the mineral is a nor- 

 mal tri-basic phosphate, an excess of bases being* com- 

 bined withSiOs. Thus: ^^/(SRCPgOs) + 2R6,Si02 

 -f ^HjO, where 7?i = 5 to 20, and p = less than 1 

 usually. 



He does not believe, as Penfield does, that the thoria 

 is originally combined with silica as thorite, but that 



* Am. Jour. Sci. (3) vol. XXIV, 1882, p. 250; vol. XXXVI, 1888, p. 

 322. Zeitschr. fur Kryst., vol, VII, 1883, p. 366; vol. XVII, 1890, p. 

 407. 



t Am. Chem. Jour., vol. IV, 1882, p. 138. 



t Zeitschr. Deutch. Geol. Gesell. Berlin vol. XXIX, 1877, p. 79.; 

 Zeitschr. fiir Kryst., vol. Ill, 1879, p. 101. 



§ Zeitschr. fur Kryst., vol. IX, 1887, p. 160; vol. XX, 1892, p.367. 



