14S A. Wandke— Intrusive Rocks of 



- First Sub-group. 



Tinguaites. — The tinguaite dikes vary from a deep 

 blue to a light gray in color. The feldspar is anortho- 

 clase. The aegerite needles which dominate the ground- 

 mass give the rock its characteristic color. 



Camptonites. — The camptonites are poorly exposed, 

 but wherever found they are characteristically developed. 

 They are full of inclusions and contain large porphy- 

 ritic crystals of glistening poikilitic hornblende. The 

 hornblende is full of feldspar and apatite. 



Paisanite. — A single example of this type of dike was 

 found near the crest of a hill just north of "Scotland," 

 York, Maine. The minerals present are quartz, albite, 

 microcline, microperthite, aegerite, riebeckite, arfved- 

 sonite, zoisite, and an undetermined titanif erous mineral, 

 brown in color and platy in habit. Both zoisite and the 

 feldspars are poikilitically intergrown.. 



Second Sub-group. 



Aplites. — The aplites, present in each of the subjacent 

 intrusives, are composed essentially of feldspar and 

 quartz, the darker minerals being sparingly developed. 

 Their composition and texture present no unusual 

 features. 



Diabases. — The diabases of the second generation 

 differ but little from those of the earlier period. They 

 are found cross cutting all of the other types of rock. 



Stocks and Batholiths. 



General Statement— "Large intrusive bodies occupy a 

 considerable part of the Portsmouth Basin. They are 

 of especial interest because of their contrasted composi- 

 tions, their contact actions, and their method of emplace- 

 ment. For purposes of easy reference these bodies have 

 been named the Rochester biotite granite; Durham 

 quartz diorite; Hampton granodiorite ; Agamenticus 

 complex, which consists of biotite granite, gabbro, sye- 

 nite, and alkaline granite ; Cape Neddick gabbro ; York 

 Harbor biotite granite; and the Brave Boat Harbor 

 biotite granite. 



