NOME VII. D. GRANITE. 



the final fragment, in the massive decomposition 

 of granite, resembles a wedge*. One rock pre- 

 sents harder projecting veins, crossing in various 

 directions ; while the softer parts are excavated: 

 perhaps a type in miniature of the granite veins 

 observable on a larger scale, when the softer in- 



tervals may have been wasted, and their place, 

 after many ages, supplied by schistus. 



This massive decomposition of granite often 

 takes place on the summits of mountains. It is 

 said that Ben Nevis, the highest mountain in 

 Great Britain, affords interesting examples of this 

 kind; but, to the disgrace of our mineralogy, 

 that mountain remains without due examina- 

 tion. 



The high ridge of Sochondo, in Chinese Ta- Sochondo. 

 tary, which gives source to the great rivers of 

 Onon and Argoon, is said to present summits 

 consisting of large rocks, piled on each other in 

 successive terraces. The mountains are proba- 

 bly granitic, like the celebrated Odon-Tchelon, 

 in Daouria, near the same river Onon, which 



* De Luc, Geologic, 305, says that granite sometimes decom- 

 poses into circular portions, the rhombs having become spheroids. 

 He saw piles of these in the Giant Mountains of Silesia, which, at a 

 distance, resembled Dutch cheeses. 



In some granites the decomposed mica becomes chlorite j but it 

 seems too bold to assume that all chlorite is decomposed mica. See 

 Journ. des Mines, iv. 42. 



