30 Geology, &fc. of the Connecticut. 



It may not be amiss to state here that the greenstone of 

 the Connecticut has a very different aspect internally and 

 -externally from the epidotic and sienitic greenstones in the 

 vicinity of Boston. The latter are evidently transition, be- 

 ing associated with the sienite, porphyry, gray wacke, argil- 

 lite, &ic. But I am not prepared to state precisely in what 

 respects they differ from the greenstone of the Connecticut. 



And although it does not strictly belong to this place, it 

 may not be amiss to refer to the interesting dyjces of basal- 

 tiform greenstone occurring in sienitic granite in the vicini- 

 ty of Boston, of which I do not recollect to have seen an 

 account. I have noticed them in Sudbury and Weymouth 

 in real granite — that is, the rock was destitute, at the place 

 of hornblende. One in Weymouth, or perhaps in Brain- 

 tree, I traced several rods, and it retained its width with 

 mathematical exactness, and the sides were perfectly 

 smooth. These dykes deserve more examination and bet- 

 ter description. Perhaps some of them contain real basalts 



White Augite. 

 Since writing the account of this mineral found in Go- 

 shen, which occurs on page 225 vol. 6. 1 have visited the 

 locality again, and find it in immense abundance. About 

 two miles north of Goshen meeting house, a few rods be- 

 yond a tavern on the west side of the road, is a pasture al- 

 most covered by bowlders of granite. These bowlders are 

 full of augite, some of the crystals of which are from twelve 

 to eighteen inches long and three or four wide, although 

 they are very imperfect. Every cabinet in the world might 

 be supplied from them. I noticed also in the same rock 

 some crystals of beryl more than an inch in diameter. 



Precious Garnet. 

 This occurs abundantly in gneiss in west and south 

 Brookfield. Some are an inch diameter ; their colour is 

 light poppy red, and it is rare to find any exhibiting the 

 form of the crystal distinctly, so that perhaps they ought 

 to be referred to pyrope. 



Prismatic Mica 

 Found in the northern part of Williamsburg in granite. 

 Good specimens may thence be obtained. 



