Caporcianite and Phakolite. 23 



Englislimen of the Daraes of Hall and Sloane, and lias been described by 

 its discoverer in his Memorie jier servireallo studio della costitusionefisica 

 della Toscana, parte '2'^, § 53. 



Caporcianite conducts itself before the blowpipe in a manner perfectly 

 similar to other zeolites, in so far as its fusibility and relation to the 

 fluxes are concerned ; but it differs from them in this much, that, previous 

 to melting, it swells out only to a very inconsiderable degree ; for it 

 melts almost at the same instant that the swelling manifests itself. 



The analysis yielded the following results : — 



Silicic acid, . 52.8 oxygen contained 27.43 8. 



Alumina, . 21.7 10.15 



Peroxide of iron, 0.1 0.03 



10.18—3. 



3.65—1. 



13.1 11.64 3. 



100.7 

 If we here express by r the monatomic bases, then the quantities of oxy- 

 gen in r, A, S, and Kq are to each other as 1 : 3 : 8 : 3, which evidently 

 determine the mineralogical formula to be r S- + 3 A S2 + 3 A q. This, 

 when transformed to the chemical formula, becomes r^ Si"^ + 3 A/ Si" 

 + 9H. 



It thns appears that Caporcianite stands chemically in near relation 

 with the minerals, Analcime, Ledererite, Potash- Harmotome, Chabasie, 

 and Levyne, from which it is separated merely by the difference in the 

 quantity of water which it contains. All these minerals consist of a bisi- 

 licate of the first as well as of the second term ; and the quantity of 

 oxygen in the alumina is in all of them three times that contained in the 

 monatomic basis. The formulae of these minerals are as follows : — 



Analcime, \ . •? a 02 o a / >■ = N. 



Ledererite, / . ' * ( r = C.N. 



Caporcianite, . r S" + 3 A S^ + 3 A ? r = C. 

 Potash-Harmotome, r S* + 3 A S" + 5 A ? r = K.C 

 Chabasie, \ . „„ „ . „„ „ . f '■ = C.N. 

 Levyne, } . '^ «' + ^ ^ ^^ "^ « ^^r = CK.N. 



The formula r S^ + 3 A S2 is thus, then, known to exist in no less than 

 four diiFerent combinations with water, namely, with 2, 8, 5, and 6 atoms, 

 the second of which results from the foregoing analysis. 



Phakolite. 



This mineral occurs in small crystals in the Bohemian Mittelgebirge, 

 and was from crystallographic investigation believed to be nearly related 

 to Chabasie. But the following analysis shews that tliis supposition is 

 not confirmed by its chemical constitution. 



