178 Dr. Berger on the physical Structure 



From these several facts we may conclude, that although quartz is 

 the oldest vein- stone, it has nevertheless been produced at different 

 periods under various forms. 



Spathose iron, though scarce, is however one of the vein-stones at 

 Beet-aktoft, 



But fiuor appears to be by far the most common vein-stone in 

 both Devonshire and Cornwall. It is more generally disseminated in 

 f)artiGles, than occurring massive : it belongs almost entirely to the 

 green variety, and differs in intensity of colour from a greenish- 

 white to a bluish-green with a dull aspect. It is of a brittle texture, 

 ^nd slightly coherent : it is foundj I believe, in the middle parts of 

 the vein, and is therefore of the most recent formation. It chiefly 

 occurs in the copper mines. 



Perhaps the different colours of the fluor may, to a certain extent, 

 have some connection with the different periods of its formation. 

 Red or pink fluor, as far as I know, has never been found but in 

 primitive countries : it has been met with in the valley of Chamouni, 

 near the glacier of Talcul, in the valley of Urseren, not far from 

 Mont St. Gothard, &c. The violet or blackish-green fluor is 

 chiefly peculiar to the stratified limestone of Derbyshire, and the 

 green variety would seem to characterize that of Devonshire and 

 Cornwall. 



Dr. Kidd mentions a bivalve shell in the mineralogical cabinet of 

 Oxford, the interior of which is lined with imperfect crystals of 

 transparent fluor,* shewing undeniably, that fluor is in some cases 



These veins (of pitch-stone) traverse the common argillaceous sandstone in Morven, 

 and are often of a great magnitude. In the island of Mull, it seems to lie between sand- 

 stone and basalt, but in Eigg it forms considerable veins traversing basalt. Jameson's 

 Mineralogy of the Scottish Isles, vol. i. 



* Kidd's Outlines of Mineralogy, part i. p. 74. 



