GMELINITE. 105 



Cleavage distinct, parallel to R. Fracture uneven. 

 Surface streaked, the prism in a horizontal direc- 

 tion, the isosceles pyramid parallel to the edges 

 of comhination with R ; R ae rough, but even. 



Lustre vitreous. Colour white passing into flesh- 

 red. Streak white. Translucent. 



Hardness = 4-5. Sp. Gr. = 2-05, BEEWSTEB. 



The Sarcolite of VAUQUELIJT, which is quite different 

 from the Sarcolite of THOMSON, is the same mineral to 

 which DE DREE has given the name of Hydrolite, and has 

 no connexion with the Analcime, as was supposed by 

 HAUY. The low degrees of hardness already remarked by 

 VAUQUELIN, and the form discovered by LEBIAN in the 

 varieties from the Vicentine, prove incontestibly that this 

 mineral agrees more nearly with the rhombohedral Kou- 

 phone-spar. The variety represented in Fig. 196 is of a 

 white colour, and marked with striae, shewing indications 

 of a regular composition according to the same law which 

 so frequently occurs in other varieties of that mineral, and 

 in Levyne. It was found by Mr ALLAN in the little deer 

 park of Glenarm, county of Antrim, Ireland, and mentioned 

 in his Synonymes; it was recognised by LESIAN as a variety 

 of the Hydrolite from the Vicentine. Two analyses of 

 the varieties from Vicenza and Castel yielded to VAU- 



&UEL1N, 



Silica 50-00 50-00. 



Alumina 20-00 20-00. 



Lime 4-50 4-25. 



Soda 4-50 4-25. 



Water 21-00 20-00. 



Dr BREWSTER found that Gmelinite possesses the proper- 

 ty of flying off in numerous scales when held in the flame 

 of a candle, and that its refractive power is lower than 

 that of rhombohedral Kouphone-spar, the index being only 

 1-474. Both in the Vicentine and in Ireland it occurs in 

 the cavities of amygdaloidal rocks. 



