372 Count DE BouRNON o« BardigUone. 



which it does form has constantly appeared to me to be at least 

 one degree smaller. 1 conceive it to be the product of the retrogra- 

 dation by five rows in breadth and four laminae in height on the 

 edges of the prism with square bases. The angle it forms with the 

 primitive planes would consequently be 128° 40. I place this crystal 

 here anew, under the aspect proper to it, because it appeared to me 

 better adapted than any other, to set in its true light the opinion of 

 the Abbe Haiiy, as well as my own ; and may more easily enable the 

 reader to decide between the two. Whichever may be adopted, the 

 crystals represented will remain the same ; the calculation alone will 

 require to be rectified, as I have myself done in the second table of 

 the modifications of the primitive crystal, annexed to this memoir. 



General Observations on BardigUone. 



From what has been said, in the preceding description of the 

 varieties of bardiglione, of the different circumstances in which they 

 present themselves, and of their localities, this substance appears not 

 to be confined to secondary strata, but also to occur in some veins in 

 primitive rocks. Such is the bardiglione that has been said to be 

 found in the vein of lead-ore at Pesai near Mont Blanc, as well as 

 that accompanied with actinote from Sweden. But hitherto it has been 

 met with much more frequently in the newer rock formations, par- 

 ticularly those that include large deposits of sea-salt. Of this kind is 

 the bardiglione which is found in the salt-works of Bex, in the salt- 

 mines at Hall, in those of Wieliczka, and in the salt-rock of Arbonne: 

 as well as that of Carinthia, Upper Austria, and Swabia. Are these 

 the only places in which this substance accompanies rock-salt ? and in 

 the great repositories of this mineral, at Voltiera in Navarre, Almen- 



