368 ON THE HIGHLANDS. 



in the ore, which seems in general tolerably 

 rich. 



The lead-glance is in lamellar distinct concre- 

 tions ; sometimes specular; sometimes small 

 granular ; and often crystallized in cubes, more 

 or less truncated on the edges and angles. It 

 is associated with quartz, felspar, copper-pyrites, 

 lamellar heavy-spar, brown-blende, and calc- 

 spar. In some specimens, the quartz appears in 

 six-sided crystals, and in prismatic distinct concre- 

 tions, which is a somewhat rare occurrence* 

 There is also calc-spar in pyramidal distinct con- 

 cretions. — The mica-slate, in the neighbourhood 

 of the vein, exhibits an unusual predominance of 

 quartz ; and the sides of the vein consist of 

 quartz with a greenish colour, which is probably 

 owing to a tinge of hornblende or chlorite 



The mode of occurrence now described, appears 

 I think, to differ somewhat from any hitherto 

 mentioned by Werner, as belonging to this class 

 of primitive rocks f . 



At Tyndrum, I found a rolled mass of dark 

 coloured hornblende-slate, containing crystals of 

 quartz and felspar, and indicating the existence 

 of a particular bed somewhere near. A few 

 miles beyond Tyndrum, the great strata of mica- 



* Mineralogical Queries by Professor Jameson, No. 16. 

 f Dr Anderson's translation of Werner on Veins, 



