268 Mr ConneH's Analysis of several Species of 



2. Laumonite, Werner^ — Diatomous Zeolite, Jamesati, 



The next mineral of which I shall give an analysis, is Lau- 

 monite, or Diatomous Zeolite. The constituents of this mineral 

 have been given by Gmelin and Vogel, as follows : 



The formula which has been given by Berzelius for its com- 

 position is, Ca^ Si^ 4- 4 A/ Si* -|- 18 H, which corresponds to, 



Silica, . . . . 50.95 



Alumina, . . . ,. ^ 22.89 



Lime, .... 8.91 



Water, .... 17.19 



The specimen of laumonite analysed by me, was from the 

 parish of Snizort, in the Island of Skye. It consisted of an ag- 

 gregation of small crystals, forming a kind of crystalline mass, 

 having a moderate degree of coherence ; the colour white, with 

 a tinge of red. 



When analysed it was in a quite fresh state^ and had not 

 suffered any of that decomposition to which this mineral is sub- 

 ject. 



The mode of analysis followed, was precisely the same as 

 that employed in the determination of the earthy ingredients of 

 the chabasite. In no instance, when it was treated with muria- 

 tic acid, did I observe any effervescence. Hence, and as it was 

 completely decomposed by the acid, it could have contained no 

 carbonic acid ; which was found to be an ingredient in the va- 

 riety analysed by Vogel. The result gave in 100 parts 



Silica, 52.04 



Alumina, . . . . 21.14 



Lime, 10.62 



Water, ..... 14.92 



98.72 



4 



