224 The Rev. S. Haughton's Notes on Mineralogy. 



the water as, added to that of the protoxides, would give the 

 formula 3 R0> 2 SiO 3 + 2 HO ; 



and such a substitution is mathematically possible in this ex- 

 ample ; I have no faith, however, in such imaginary combinations. 

 The Stilbite (No. 2) occurred in flat radiated crystals, readily 

 distinguishable by the eye as those of Stilbite. Its analysis 

 gave — 





No. 2. Stilbite 



Oxygen. 





Silica . 



58-20 



30-217 





Alumina . 



15-60 



7-291 





Lime 



8-07 



2-294"] 





Magnesia . 



none 





>2'574 



Soda 



0-49 



0-125 



Potash . 



0-92 



0-155, 





Water . . 



18-00 



16-000 





101-28 56-082 



This analysis gives very well the usual formula of Stilbite, 

 regarded as an hydrated lime orthoclase, 



RO, Si0 3 + Al 2 3 ,3Si0 3 + 6HO. 



The foregoing analysis may be compared with that of very 

 finely-crystallized Stilbite, found by Mr. Jacob in the Nerbudda 

 Valley, which was published by me in Note V. on Mineralogy, 

 in the Philosophical Magazine for July 1857. 



The next mineral to be described is especially interesting, 

 because it seems to set at rest the controversy as to the specific 

 identity of Hypostilbite, and fully establishes the title of that 

 mineral to be regarded as a distinct species, and not a degrada- 

 tion of Stilbite produced by hydrous metamorphism. It occurs 

 in large, fibrous, transparent masses, radiated like Natrolite or 

 Thomsonite, and filling globular cavities in green trap. 



No. 3. Hypostilbite. Spec. grav. = 2*180. 



Oxygen. 



^2-854 



98-75 54-731 



This analysis is very like that published by me, of a specimen 

 of Hypostilbite from Skye (Phil. Mag. July 1857), and also re- 

 sembles the original analysis of Beudant. It may be regarded 

 as an hydrated lime oligoclase, with the formula 

 EO, Si0 3 + Al 2 3 , 2 SiO 3 + 6 HO. 



Silica . 



. 52-80 



27-414 



Alumina . 



17-12 



8001 



Lime 



7-89 



2*242" 



Magnesia . 



trace 





Soda . . 



2-35 



0-601 



Potash . . . 



007 



0011 



Water . . 



18-52 



16-462 



