MODE IX. GYPSUM. 485 



aince the formation of the secondary mountains. 

 The specimens which I possess are of a nature 

 to justify this idea; their texture is not homo- 

 genous ; the mica does not appear to have been 

 united to the gypsum by a simultaneous crystal- 

 lisation : it is in plates nearly incoherent, which 

 separate thin layers of an argillaceous sediment. 

 This mica then seems to have been brought 

 down and deposited by the waters, rather than 

 crystallised in them. Nevertheless, as I have 

 not observed it in its native site, I dare not be 

 too decided in this opinion." * 



This gypsum was observed by Saussure in 

 passing from Bellinzona to St. Gothard ; but we 

 are told by Brochant and Jameson that the pri- 

 mitive gypsum was discovered near Bellinzona; 

 and they add, that it is in layers between beds of 

 mica slate ; and Jameson says, along with lime- 

 stone and hornblende slate. I know not their 

 authority for this assertion; but the objections 

 of Saussure seemed to Patrin so powerful, that 

 he virtually denies the existence of primitive 

 gypsum, by asserting that it is wholly tertiary. 

 The mixture indeed of mica is of little conse- 

 quence, as it is found in the most recent sand- 

 Atones ; and even that of felspar, as observed by 



* 1931. 



