115 



reason ; the principal reason that I would give being that of the 

 discovery by Professor Harkness of the characteristic hopper-shaped 

 pseudomorphs of the crystals of this mineral in the New Red 

 Rocks of the Eden Valley. Doubtless, when the Stanwix Marls 

 come to be thoroughly explored we may succeed in meeting with 

 existing crystals of the salt itself; if it should not be proved to 

 occur in the more commercially-important form of regular beds. 

 The origin of Rock salt has given rise to many different theories ; 

 but that most commonly accepted is the one advocated in 

 Sir Andrew Ramsay's Physical Geology of Great Britain. In an 

 address to the Carlisle Scientific Society on the " Penrith Sand- 

 stone," delivered at Nunnery Walks in the summer of 1880, I gave 

 a resume of these theories, with some additional remarks bearing 

 upon this important subject. 



IV. 



In the Fourth, and remaining Division are placed the compounds 

 of the Elements with Oxygen. This group includes all the chief 

 rock-forming minerals of our district, as well as some of the mineral 

 compounds that are of much importance in an economic respect. 



Protoxides. 



In the British Museum list the first of our minerals included in 

 this category is Melaconite, Tenorite, or Copper Monoxide. 

 Townshend Hall states that this ore of copper occurs at Roughten 

 Gill along with Chalcopyrites (" Towanite") and Brewsterite. I 

 have not seen a specimen of Melaconite from any of our localities, 

 but there is every reason for expecting to meet with it under the 

 circumstances that obtain at Roughten Gill and the neighbour- 

 hood. 



Sesquioxides. 



In Hall's Mineralogist's Directory Corundum, Aluminium-Sesqui- 

 oxide, is mentioned as occurring along with Tourmaline at Carrick. 

 This mineral, which amongst its varieties includes the Sapphire 

 and the Ruby, as well as the Emery employed in the Arts, is, next 



