LARSEN AND WHERRY: LEVERRIERITE FROM COLORADO 213 



No satisfactory interpretation of this remarkable constancy of 

 optical properties with wide difference in H 2 content occurs to 

 the authors. The loss of water of crystallization or of chemically 

 combined H 2 should have a considerable influence on the optical 

 properties and would be expected to be accompanied with a 

 complete change in all the crystal properties. Even the loss 



TABLE 3 

 Analyses of Minerals of the Leverrierite Group 



Si0 2 .... 



A1 2 3 ... 



Fe 2 3 ... 



MnO... 



CaO.... 



MgO... 



Na»0... 



K 2 0.... 



H 2 0+1 



H,0-J 



Totals 



Al 2 3 :Si0 2 . 



1 



47.28 



20.27 



8.68 



2.75 

 0.70 

 0.97 

 tr. 



19.72 



100.37 



47.84 



20.88 

 8.48 

 0.24 

 2.52 

 0.91 

 1.58 



tr. 

 6.65 



10.95 



100.05 



47 

 20 

 8 

 

 2 

 

 1 



6 

 12 



.56 

 .57 

 .58 

 .24 

 .52 

 .80 

 .28, 



.65 

 .01 



100.21 

 1 : 2.76 



3a 



789 

 256 



89 



47.95 



32.67 



0.23 



0.41 

 0.46 

 2.47 

 0.24 

 7.03 

 8.56 



99.36 

 1 : 2.34 



49.90 



37.02 



3.65 



tr. 

 0.30 



1.13 



8.65\ 



? / 



100.65 

 1:2.11 



50.55 

 19.15 



4.40 

 0.63 



24.05 



98.78 

 1:3.95 



49.4 

 45.1 



5.6 

 ? 



100.1 

 1: 1.86 



48.43 

 41.63 



2.13 



7.70 

 ? 



99.89 

 1: 1.94 



1 and 2. Material from Beidell, Colorado. New analyses by E. T. W. 



3. Average of 1 and 2. 



3 a. Molecular proportions of 3. 



4. Average of 2 analyses of "rectorite," Garland County, Arkansas. Brackett, 

 R. N., and Williams, J. F., Amer. Journ. Sci., 42: 16. 1891. 



5. Leverrierite, Rochelle, France. Termier, P., Bull. Soc. Min., 22: 29. 

 1899. Analysis made on material dried at 110°-130°. Older analyses show 13.21 

 and 18.0% of total water. 



6. "Montmorillonite, var. delanouite," Millac, France. Quoted from Lacroix, 

 A., Mineralogie de la France. 



7. "Batchelorite," Tasmania. H 2 stated as "combined H 2 0." Gregory, 

 J. W., Trans. Austr. Inst. Min. Eng., 10: 187, 1905. 



8. Kryptotile. Quoted from Dana. The original article reports H 2 without 

 a statement as to whether it represents total water or water above 100°. 



of 17.4 per cent of "absorbed" H 2 would be expected to cause 

 a considerable change in the values of the indices of refraction. 

 Composition. Two different samples shown by microscopic 

 examination to be essentially homogeneous were analyzed by 

 standard methods and yielded the results shown in columns 1 



