a New Mineral Species of the Zeolite Family. 287 



Its hardness is — 4.5, between fluor and apatite ; the speci- 

 fic gravity I found to be = 2.249 in several small crystals ;= 

 2.250 in a single larger specimen ; both of them at a tempera- 

 ture of 10* R. 



Before the blowpipe, the indications given by epistilbite 

 are the same as in stilbite and heulandite. In the mattrass, 

 it intumesces considerably, and gives off water. On char- 

 coal, it froths up, and forms a vesicular enamel, but cannot 

 be melted into a globule. Borax dissolves a great quantity 

 of it, and forms a clear globule. It is likewise soluble in sal 

 of phosphorus, with the exception of a silica skeleton. With 

 solution of cobalt the enamel becomes blue. 



The epistilbite is soluble in concentrated muriatic acid, 

 with the exception of a fine granular residue of silica. After 

 ignition it is insoluble. 



The chemical composition, obtained by analysis, is as fol- 



follows — 



Silica, - 68.59 containing oxygen 30.44 - 12 



Alumina, - 17.52 8.18 - 3 



Lime, - 7-56 2.12) 



Soda, - 1.78 0.45/ " l 



Water, - 14.48 12.87 - 5 



The corresponding mineralogical formula is -= > S 5 + 3 



AS 3 + 5 Aq. 



Observations. 



Several years ago I observed and measured the crystals 

 of epistilbite in the Royal Collection of Berlin. Even before 

 this period, Professor Weiss had placed by themselves, as anew 

 variety of foliated zeolite, some specimens of it, which, how- 

 ever, were not very distinct. The variety which I first ex- 

 amined, occurs in small but simple crystals, along with larger 

 crystals of heulandite. Afterwards, in 1824, I recognized 

 this species in Paris, where Count Bournon likewise had con- 

 sidered it as something new. He allowed me to institute 

 some measurements with these crystals, which I found to 

 agree exactly with those I had obtained before. I feel par- 

 ticular pleasure, in having this opportunity of public- 

 ly expressing my gratitude to Count Bournon, for the ex- 



