SCHALLER: FRENCH PHOSPHORITE MINERALS 



151 



the color changes has been found. The analysis and ratios i 

 as follows : 



arc 



The ratios lead to the accepted formula A1 2 3 P 2 5 4H 2 0. 



MINERALOGY. — Chemical composition of the French phosphor- 

 ite minerals. Waldemar T. Schaller. To appear in a 

 bulletin, " Mineralogical notes, Series II." of the U. S. Geo- 

 logical Survey. 



The mineralogy of the French phosphorite deposits has been 

 fully described by Lacroix in two recent publications. 1 He shows 

 that the three minerals of which these phosphorites are composed 

 are collophanite, dahllite (syn. podolite) and francolite (syn. 

 staffelite). The formulas of these minerals, as generally given, 

 are as follows: for dahllite 6CaO 2P 2 5 CaC0 3 |H 2 0; for francolite 

 lOCaO 3P 2 5 CaF 2 C0 2 H 2 0; and for collophanite 3CaOP 2 5 .- 

 H 2 (Dana) or, since C0 2 has been shown to be an essential con- 

 stituent of the mineral, x[3CaOP 2 5 ] or .r[9CaO 3P 2 5 CaF 2 ] 

 + yC&COs + zH 2 (Lacroix). 



A study by the writer of the analyses of these minerals has 

 shown that their formulas are more probably as follows: dahl- 

 lite 9CaO 3P 2 5 CaO. C0 2 H 2 0, francolite 9CaO 3P 2 6 CaF 2 C0 2 

 H 2 and collophanite 9CaO 3P 2 5 CaO C0 2 H,0 + nH 2 0. 



^omptes rendus, 150: 1213. 1910; Mineralogie de la France, 4: 555. 



1910 



