Hyland — On the Mesolite [Galactite) of Kenbane Head. 413 



or the relation Na 2 . A1 2 3 . 3Si0 2 . 2H 2 0, when the lime is consi- 

 dered as replacing the soda. 



This formula demands as is well known — 



Si0 2 .... 47-20 



A1 2 3 .... 27-00 



Na 2 .... 16-30 



H 2 .... 9-50 



100-00 



It seems, however, more rational to consider the analysis as 

 expressing a mixture of natrolite and scolezite, such as is repre- 

 sented by the variety of natrolite called galactite. Reckoning the 

 formula of natrolite as Na 2 (Al 2 )Si 3 Oi + 2H 2 0, that of scolezite as 

 Ca(Al 2 )Si 3 Oio + 3H 2 0, the mineral from Kenbane Head maybe 

 said to contain — 



Scolezite-substance. Natrolite-substance. Reckoned. Found. 



81-36 



99-51 100-02 



18-15 

 This is equal to — 



(4-5 or 9 Na,(Al 2 )Si 3 O I0 + 2H 2 0) ( 

 ( 1 or 2 Ca (Al 2 )Si 3 O 10 + 3H 2 0) j 

 Heddle 1 gives the following analysis of the galactite of Bishops- 

 town : — 



Si0 2 



A1 2 3 



Fe 2 3 



CaO 



MgO 



Na,0 



H 2 



100-55 



99-85 



1 Phil. Mag., 4th ser., vol. xi., 1856, p. 272. Behaves optically like Mesotype 

 (Descloizeaux). 



2 Handbuch der Mineralchemie. Erganzungsheft zur 2ten Aufl. Leipzig : 1886, 

 p. 164. 



