264 Dr Brewster's Description of G melinite , 



he considered as the same substance.* As I had devoted 

 much attention to the examination of the Analcime and the 

 Chabasie, Mr Haidinger was so good as to put into my hands 

 this interesting specimen, and also a specimen of the flesh-co- 

 loured masses from the Vicentine. The slightest comparison of 

 these substances in their optical characters, put it beyond a 

 doubt, that they had no relation to Analcime or Chabasie, and 

 that the whitish crystals from Glenarm were similar to the 

 flesh-coloured masses from the Vicentine, and formed a new 

 and a very interesting mineral species. 



To this species I propose to give the name of Gmelinite, in 

 compliment to G. C. Gmelin, Professor of Chemistry in the 

 University of Tubingen, whose analyses of minerals have 

 ranked him among the first analytical chemists of the present 

 day, and whose friendship I am happy to have the present 

 opportunity of acknowledging. 



This new species comprehends the flat six-sided prisms 

 from Glenarm, and the flesh-coloured masses which accom- 

 pany them ; the flesh-coloured mineral from the Vicentine, 

 and probably the six-sided prisms observed by Leman. 



The Gmelinite from Glenarm crystallises in the form shown 

 in Plate VIII. Fig. 2, which is a regular hexagonal prism, 

 terminated at both ends by six-sided pyramids, with flat sum- 

 mits. The following are the angles of the crystal, taken with 

 the reflective goniometer. See Plate VIII. Fig. 2. 



u upon y 131° 48 



o y 138 14 



u ii 120° 



y y' 9S J 24 



Rhombohedral. Combination P — cc. P. P + oc. The 

 angles of the isosceles pyramid = 145° 54', 71° 48 7 . 



Cleavage distinct, parallel to It. Fracture uneven. Sur- 

 face streaked, the prism in a horizontal direction, the isosceles 

 pyramid parallel to the edges of combination with R ; R — oo 

 rough, but even.-f- 



The flesh-coloured Gmelinite, from the Vicentine, has 

 more than one cleavage. It is very imperfectly crystallized ; 



* Mineralogical Nomenclature, Edit. 1819, Voc. Analcime. 

 t For this character of the combination and cleavage, as well as the fi- 

 gure, I have been indebted to Mr Haidinger. 



