524 



PITCHSTONE, 



THE information which is to be obtained 

 respecting- this rock, is neither very abundant 

 nor very accurate. The causes of this must be 

 sought for, partly in its rarity, and partly, it is 

 probable, in the prevalence of certain hypothe- 

 tical opinions respecting its origin and connec- 

 tions, similar to those which have been equally 

 the source of confusion in the history of many 

 members of the trap family. The slender sketch 

 of its connections here given, is therefore drawn 

 solely from the writer's observations ; and the 

 reasons for mistrusting those which have not 

 been verified by his own experience, will shortly 

 appear. 



In its geological connections, as well as in 

 some of its mineral characters, it approaches 

 very nearly to many members of the preceding 



