244 J. B. Mackintosh — Iron Sulphates from Chili. 



Ratio. 



S0 3 41-24 2-001 



Fe o 3 . 41-22 1-000 



H 2 [17-54] 3-78 



Formula Fe 2 3 , 2S0 3 , 4H 2 



Water lost at 110° C. = 0-304 molecule, leaving a residue 

 containing 3 - 48 molecules. The result of heating this mineral 

 is the same as of heating amarantite. They only differ by 3 

 molecules H 2 0, but there is no apparent structure like amaran- 

 tite to indicate that the one is a direct product of dehydration 

 of the other. 



6. Ferronatrite (No. 11). — The analysis of this mineral I have 

 recently completed, having received it from Prof. Egleston 

 only a short time since. It occurs in stellate groups of a pale, 

 whitish green color, forming nearly spherical nodules ; it is in 

 general similar to pale wavellite in appearance. It is associated 

 with copiapite and coquimbite. Analysis : 



Ratio. 



S0 3 50-25 6-281 



Fe„0 3 17-23 1-077 



A1 2 3 0-43 0-042 



Na 2 18-34 2-958 



K 2 0-40 0-042 



SiO„, etc., insoluble 2*00 



H„0 11-14 6-189 



99-79 



Formula 3Na 2 0, Fe 2 3 , 6S0 3 , 6H 2 



Water lost at 110° = 5|- molecules, the residue dissolves readily 

 in water. This mineral is somewhat similar to sidero-natrite, 

 Na 2 0, Fe 2 O s , 3SO s , 6H 2 0, to urusite, 2Na 2 0, Fe 2 0„ 4SO s , 

 8H 2 and to bartholomite, 2Na 2 ; Fe 2 3 , 4S0 3 , 2H 2 0, but dif- 

 fers from them in being soluble in water and being a neutral 

 instead of a basic salt. It is quite analogous, however, to 

 Krohnkite,* the double sulphate of sodium and copper if we 

 can consider that the copper may be replaced by its equivalent 

 in ferric iron without destroying the analogy. The relationship 

 is clearly shown by the formulae, taking 3 parts of Krohnkite. 



Krohnkite 3 (Na 2 0, CuO, 2S0 3 , 2H 2 0) 



Ferronatrite (new mineral) 3Na 2 0, Fe 2 3 , 6S0 3 , 6H 3 



7. Associated with these minerals are several white pulveru- 

 lent sulphates which are apparently alteration products, but 

 which nevertheless possess some points of interest. Of these 

 the first gives the following results on analysis. White, pul- 

 verulent (No. 4), sp. gr. not taken. Analysis : 



* Cf. Darapsky, Jahrb. f. Min., i, 192, 1889. 



