434 Dr. Mac Culloch on the Geology of 



crystal. It is perfectly evident, that whatever is true of the above 

 cited granite veins, must also be true of this rock, that the schorl 

 has been crystallized, then broken, and penetrated by quartz in a 

 state of fluidity. Nor is there any intermixture of the matter of 

 quartz, with the matter of schorl, but the line of separation is 

 most accurately drawn between them. It follows then from these 

 circumstances, that the rock in question is not a simultaneous 

 formation from a state of fusion, nor can we readily understand 

 how it can be the effect of fusion at all, consistently with the 

 chemical principles we acknowledge. Had such a mass of fused 

 quartz invaded the minute fragments of schorl which the specimen 

 exhibits, the latter must either have been fused into a shapeless 

 mass, or at least the asperities of fracture could not have remained 

 in a substance whose fusibility is so much lower than that of 

 quartz. Those who attribute the formation of this rock to aqueous 

 solution, will perhaps in the above mentioned specimens find 

 arguments in favour of their hypothesis. I will not repeat the 

 often quoted difficulties which attend this theory also, but request 

 from it an explanation of the remaining specimens. 



The first of these is from the same vein at Portsoy, and contains 

 an acicular and detached cr}^stal of schorl, which is bent without 

 fracture, so as to form a considerable curvature. 



As chemistry produces no examples of incurvated crystallization, 

 I may safely conclude that this crystal has been bent by external 

 force after its formation. The noted fragility of schorl will not 

 allow us to suppose that it could be bent without breaking, unless it 

 "had been previously rendered flexible by some chemical agent 

 possessed of powers which we have not hitherto discovered in water. 



The other specimens are not from Portsoy, but from an interior 

 part of the country, and exhibit appearances equally irreconcilable 



