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ON THE ROCKS OF SANDSIDE 



XIII. — On the Rocks of Sandside in Caithness. 



By Professor Jameson. 

 (Read 2teh December 1819J 



The crust of the earth is almost entirely compo- 

 sed of five simple minerals, viz. Quartz, Felspar, 

 Mica, Limestone, and Hornblende These, ei- 

 ther variously aggregated, or in simple unmixed 

 masses, form the various kinds of mountain-rocks. 

 All the other simple minerals described in Systems 

 of Mineralogy, occur in comparatively small quan- 

 tities, distributed through these mountain-rocks, in 

 the form of beds, veins, imbedded masses, disse- 

 minated, or in drusy cavities. Of the five simple 

 minerals already enumerated, the most generally and 

 widely distributed are quartz and felspar; lime- 

 stone is more abundant than mica and hornblende ; 



* Under this title I also include, in a geognostic sense, 

 Augite. 



