GEOLOGICAL AND MINERALOGiOAL NOTES. 113 



more or less thickly scattered. In some of the outcrops 

 these crystals are tabular, so that there is a conspicuous 

 development of the clinopinacoid plane, giving the surface 

 a decided porphyritic appearance, while in other places 

 crystals showing the basal plane are more abundant, giv- 

 ing the surface of the rock-mass a distinctly tessellated 

 appearance. 



H. MACROSCOPICAL CHARACTERS. 



The rock in the hand specimen is extremely variable. 

 Specimens from the southern end of West beach, from 

 West Manchester and from Winter island are of a decided- 

 ly coarse well crystallized felspathic rock with a little horn- 

 blende and biotite. Numerous specimens from various 

 outcrops in Salem, Beverly, Essex, Manchester and Glou- 

 cester of the more typical rock are all of a decidedly simi- 

 lar type, being composed of coarse well crystallized 

 minerals, the recognizable ones being orthoclase, pyroxene, 

 hornblende, biotite, magnetite and a little quartz. The 

 color of these specimens is a grayish green. At other out- 

 crops, as on the hill in the city of Gloucester, which is 

 used for the purpose of road building, at Powder House 

 hill in Essex, at a cutting on the road side in Lanesville, 

 opposite Young avenue, and at Poor House hill in Beverly, 

 this rock is of a dark green color, almost black, which, 

 if examined with the pocket lens and with the usual field 

 apparatus could only be considered a porphyritic pyroxene- 

 hornblende rock. At Thompsonville in Essex, and ex- 

 tending to the Loaf on Coffin's beach and nearly the whole 

 length of the Squam river, there are varieties of the augite- 

 syenite rock. Other outcrops are found at Wheeler's 

 Point, Pierce's island, Rust's island, and by the roadside 

 towards Coffin's beach in West Gloucester, and also in the 

 cellar of the Eussia cement works in West Gloucester. At 



