SCHALMCR.] 



Minerals from Leona Heights. 



215 



about 20° and were possibly melanterite. The amounts of fer- 

 rous iron, magnesia and alumina varied somewhat in different 

 samples. The average of several analyses of this material gave 

 the following results: 





Analysis. 



Ratio. 



Pe 2 3 



25.04 



15.65 \ 



A1 2 3 



0.31 



0-30 ( _ 



FeO 



0.44 



0.61 ( 



MgO 



0.29 



().7:i ) 



so, 



38.36 



47.95 = 5 



H,0 



29.71 



165:06 = 19 



Insol. 



5.43 







99.58 





.0 



A fractional determination of the water gave: 



H 2 (at 110°) 20.25 



" (at 150°) 3.10 



" (at 200°) 2.26 



" (at 260°) 1.77 



" (above 260°) 2.33 



29.71 



These water determinations were not carried out very accur- 

 ately but they show that about two-thirds of the water is given 

 off at 110°. To assume that exactly two-thirds or 12 molecules 

 of the water are given off at 110°, which is probably water of 

 crystallization, would give us, for the formula of copiapite, 

 2Fe203.5S03.6H 2 0+12H 2 0. If, now to obtair the acid of 

 which copiapite is the ferric salt, we substitute for Fe its 

 equivalence 3H, we obtain 2(3H) 2 3 .r>S0 3 .6H 2 0+12H 2 0. 

 Neglecting the twelve molecules of water of crystallization, and 

 reducing the first part of the formula, we obtain 6H 2 0.5S0.3 

 6H 2 0=5H 2 S04.7H 2 as the acid from which copiapite is derived 

 — a very improbable acid. 



If, however, we assume that fourteen molecules of the water, 

 instead of twelve, are water of crystallization, we then have 2Fe 2 C>3. 

 5SO3.4H2O+I4H2O. as a formula for copiapite. Again substi- 

 tuting 3H for Fe'", this becomes 6H 2 0.r)SO :! .4H 2 0+14H 2 0. , or, 

 neglecting the fourteen molecules of water, 2H2O.SO3 = H2SO4. 

 H 2 0, which latter is tetrahydroxyl sulphuric acid, as the acid of 

 which copiapite is the ferric salt. This formula would require 



