244 SERPENTINE. 



tected ramifying from masses of serpentine. As 

 far as is yet known, it seems to form irregular 

 masses included among the primary strata, and 

 resembling those which are sometimes found in 

 the primary limestones. Rarely, it is included 

 immediately in granite, occurring in that situa- 

 tion in Aberdeenshire. 



These masses vary in size, sometimes extend- 

 ing for miles, and, at others, not exceeding a 

 few feet in dimensions. In the latter case, they 

 frequently put on a parallel figure, determined 

 by that of the strata in which they lie, but not 

 persistent, inasmuch as they are extenuated at 

 the edges till they disappear. 



The strata among which masses of serpentine 

 occur in this country are chiefly gneiss, argilla- 

 ceous schist, hornblende rock, and limestone ; 

 it is also found rarely and sparingly in micaceous 

 schist. In the case of their contact with argilla- 

 ceous or micaceous schist, a change of the in- 

 cluding rock takes place near the junction, by 

 the intervention of the talc which is so often as- 

 sociated with this substance. In the same way, 

 the neighbouring masses of gneiss assume a pe- 



