On flic Genesis of Some Scottish Minerals. 183 



one or more of whose constituents are transferred from 

 above downwards. 



A 1. Those whose first stages consist in their being 

 dissolved at the surface, and then redeposited 

 elsewhere outside the lithosphere. 

 {a) Those deposited on the land. 

 (^) „ „ in fresh water. 



(c) „ „ in closed bodies of water. 



(d) „ „ at the bottom of the sea. 



A 2. Those whose materials arise through solution at the 

 surface, and subsequent redeposition within the 

 lithosphere. 

 A3. Those due to subterranean percolation of waters 

 from the surface. 



(a) Those which are there altered in sit4. 

 (h) Those whose materials have been dissolved 

 within the lithosphere, and subsequently 

 redeposited at lower levels. 

 II. Hypogene Minerals.— Mostly of hydro-thermal origin, 

 and usually connected with some manifestation of elevatory 

 movepient. 



B 1. Original Minerals of Eruptive Rocks. 



(a) Silicates. 



(b) Metals and their Compounds. 



(c) Other Minerals. 



B 2. Original Contents of Mineral Veins. 



B 3. Minerals arising from Solfataric Action. 



B 4. Those deposited at the surface by Thermal Springs. 



B 5, Those arising through Thermo-Metamorphism. 



B 6. Minerals arising through Dynamic Metamorphism. 



B 7. Combinations of the effects of B 5 with those of B 6. 



It will probably be found on examination that there are 

 few, if any, minerals occurring in Scotland whose origin 

 cannot be referred to one or other of the above categories. 

 In a few cases, as might have been expected, the same 

 mineral species has arisen in more than one way. Haematite 

 is a good example of this : usually it is due to the replacement 

 of calcareous matter by the action of ferriferous solutions 

 percolating downward, chiefly under desert conditions (A 2) ; 



