82 Count de Bournon on the Latimomie. 



state is beautifully transparent, but it is extremely rare to meet with 

 it in this condition, in consequence of , the great facility and rapidity 

 with which its alteration proceeds. 



3. Phosphorescence. This substance does not possess any sen- 

 sible phosphorescence ; however, as it is accompanied, and even in- 

 termixed, with a highly phosphorescent lamellar carbonate of lime, 

 the luminous appearance of which is a bright reddish yellow or 

 orange, it is liable to have some portions of this carbonate of lime 

 interposed throughout Its substance, which is the cause of its being 

 sometimes observed, that fragments of it when submitted to trial 

 give traces of a slight phosphorescence. 



Observations on the crystallisation of the Laimionite. 



If this substance offer a striking peculiarity, and one very proper 

 to entitle it to a distinct place in the classification of mineral substan- 

 ces, by the facility with which simple exposure to the atmosphere 

 causes it to undergo disintegration, and finally to fall into powder ; 

 its crystallisation, which cannot be referred to that of any other 

 known mineral, adds still more to the singular characters which the 

 laumonite exhibits. This crystallisation generally appears in the 

 state of crystalline masses, often of considerable size, and which at 

 first sight present only a deeply striated or fasciculated surface ; but 

 these same masses, which apparently have no determinate crystalline 

 forms, on being broken become immediately a rich field of observa- 

 tion by the great quantity of extremely perfect and diversified crys- 

 tals, which the portions into which they divide, afford. They are 

 therefore, at least with regard to a great number, merely a confused 

 aggregation (arranged however in the direction of their prisms) 

 of crystals perfectly formed, and of different shapes, piled one above 



