A. F. Rogers — Collophane, 



273 



Odontolite, also known as bone turquois or occidental 

 turquois, is an alnminons variety of collophane, according 

 to Lacroix. 12 



The nanrnite of Elschner 13 is typical collophane. The 

 formula 3CaP 3 O s .Ca(OH,F) 2 is assigned to it, bnt speci- 

 mens presented to Stanford University by Dr. Elschner 

 contain about five per cent carbon dioxide and are entirely 

 free from calcite, aragonite, or dolomite. This beautiful 

 brown, banded, resinous mineral from the island of Nauru 

 is the best and most typical form of collophane that it has 

 been my privilege to see. 



The Chemical Composition of Collophane. 



There are very few complete analyses of phosphorites 

 on record ; most of the analyses are evidently commercial 

 ones in which insufficient care was made in selecting the 

 material. The writer has with some difficulty succeeded 

 in collecting five fairly complete analyses of collophane, 

 which were probably almost free from mechanical 

 impurities. 



Analyses of Collophane. 









Fe 2 3 . 

















CaO 



MgO 



A1 2 3 



P 2 5 



C0 2 



F 2 



S0 4 



H 2 



Iusol. Total 



1. 



50.70 



0.80 





39.10 



3.96 







5.02 



99.58 



2. 



52.47 



0.21 



0.53 



38.72 



1.88 



1.60 



0.22 



5.00 



99.65 



3. 



49.73 





0.50 



37.40 



3.75 



0.88 





7.05 



99.24 



4. 



51.85 







37.60 



4.00 



1.50 





4.80 



99.12 



5. 



50.97 



0.22 



0.76 



36.35 



1.72 



0.40 



2.98 



1,05 



1.82 99.04* 





1, Sombrero. 2, 



, Nauru. 3, Pouzillac, 



France. 



4, 



Mouillac, 



France. 5, 



Crawford Mts., Utah. 

 ♦Includes 2.00 Na 2 0, 0.47 K 2 and 0.30 SiO, 



1. 904 



936 



886 

 924 

 908 



Ratios from Collophane Analyses. 



CaO MgO Fe 2 3 A1 2 3 P 2 £ 





CO, 



F, 



S0 4 



H 2 





— 



275 



90 







— 278 





— 



272 



43 



84 



3 278 



2 



3 



263 



85 



46 



— 392 



2 



3 



264 



91 



39 



— 266 



2 



6 



256 



39 



21 



Na 2 0: 



37 58 

 = 32 ; K 2 = 5, 



12 Mineralogie de la France, p. 577, 1910. 



13 Corallogene Phosphat-Insel Austral Oceanien und Ihre Produkte, Liibeck, 

 1913. 



