154 GEOLOGICAL RECONNOISSANCE 



The water was determined by heating the mineral in a small glass 

 retort, the neck of which was connected with a chloride of calcium tube. 

 The experiment gave 11.808 per cent, of water; this deducted from the 

 total loss by ignition gives the carbonic acid; hence, the composition is: 



Oxide of zinc 73.202 



Water 11-808 



Carbonic acid 15.010 



100.080 



The only mineral known consisting of oxide of zinc, carbonic acid, 

 and water, is Smithson's " zinc-bloom," for which the formula 

 3 ZnO.C0 2 -j-3 HO has been constructed. This formula requires: * 



Found by Smithson. 



Oxide of zinc 71.28 69.38 



Carbonic acid 12.89 13.50 



ater 15.83 15.10 



100.00 97.98 



Yon Kobell § constructed for this mineral the formula 

 3 [2 ZnO.C0 2 ]-j-2 [Zn0.3HO], which does not agree with Smithson's 

 analysis, and which, therefore, cannot be considered as expressing the 

 composition of zinc-bloom. But Von Kobell's formula agrees very well 

 with the analytical results obtained by me for the above-described mineral, 

 which has to be considered a new species, or at least a new variety of 

 zinc-bloom, and for which 1 propose the name of " Marionite." f 



In 100 Found 



8 Zn O 324.24 72.99 73.2G2 



3 CO 2 66.00 14.86 15.010 



6 HO 54.00 12.15 11.808 



444.24 100.00 100.080 



Blende (sulphuret of zinc), occurs abundantly at Wood's mine. It is 

 mostly of dark brown color, and large crystals are frequently found 

 cemented by irregular masses of impure smithsonite. In some specimens 

 the blende presents a cellular appearance, as if acted upon by a dissolv- 

 ing liquid; the cavities are generally coated with a layer of minutely crys- 

 talline carbonate of zinc, of gray or reddish color. 



* v. Dana's mineralogy, 4th ed. p. 400. 

 § v. i; , ■ Handworterbuch, etc., vol. 2, p. 205. 



Want of material prevented a repetition of the analysis. 



