SCHALLKR.] 



Minerals from Leona Heights. 



211 



The 



analysis of the 



massive minera 



[ gave the 



followin 



results : 













Analysis. 



Insol. deducted. 



Ratio. 



Calculated. 



CuO 



27.52 



28.53 



1.00 



27.85 



FeO 



0.27 



0.28 







MgO 



trace 



trace 







80 3 



27.63 



28.65 



1.00 



28.02 



HoO 



42.21 



43.76 



6.78 



44.13 



Insol. 



3.54 











101.17 



101.22 





100.01) 



The ratio of CuO : S0 3 : H 2 <) in both is 1:1:7; j of the water or 

 6 molecules being given off at 105? This mineral may then also 

 be considered as a salt of tetrahydroxyl sulphuric acid. The 

 formula for boothite then becomes CUSO4.H2O + 6H2O, or, 

 writing it structurally, 



/g>Ou 



os ( ; + 6 h 2 o. 



\g>H 2 



As has been shown for manganese sulphates,* the amount of 

 water of crystallization depends on the temperature at which 

 crystallization takes place. The same law doubtless holds good 

 for copper sulphate. It is probably due to this fact that we have 

 a copper sulphate crystallizing with seven parts of water instead 

 of five. The temperature at which this septahydrate of copper 

 forms is probably near 0° C, a temperature which must often be 

 reached in the Alma mine. 



The name boothite is proposed for this new sulphate of 

 copper, in honor of Mr. Edward Booth of the Department of 

 Chemistry, University of California, who was the first to direct 

 the writer's attention to this deposit of sulphates. 



The three minerals, melanterite, pisanite and boothite, form 

 an isomorphous series whose general formula may be written, 

 R8O4.H2O+6H2O. They are all monOclinic and their axial 

 ratios vary but little. 



Melanterite 



Pisanite 



Boothite 



1.1828 

 1.1670 

 1.1622 



1.5427 

 1.5195 

 1.5000 



104° 16' 



104 30 



105 36 



*Dr. F. G. Cottrell, Journ. of Phys. Chem., Vol. IV, p. 637, 1900. 



