licli i 



186 T. 8. Hunt— Notes on Granitic Rochs. 



is bounded by a band of more tlian lialf an inch of fine-grained 

 granite with yellowish -green mica, presenting larger crystals of 

 feldspar near the outer margin, wdiere it is succeeded bv a ]:iT.r 

 of pure smoky vitreous quartz of about the same tl'ii/. ' 

 whose outer surface, against the wall, shows irregular In 

 nodular masses, the depressions between which are occuj 

 a finely granular micaceous aggregate unlike anv other \ . 

 the vein in texture. This description may be read in e>;.... 

 tion with the remarks in § 27. 



Dana has described and figured a similar granitic vein; bandd 

 with quartz, observed by him at Valparaiso in Chili, (Manual of 

 Geology, 1862, p. 713),*' and has moreover maintained that such 

 granitic veins, like ordinary metalliferous lodes, are clearly con- 

 cretionary in their- origin, and have been filled by slow and sue- 

 (osits from aqueous solutions. His testimony to tbe 

 1 1 have advocated in this paper had been overlooked 

 by me, or it would have been noticed in § 12. 



§ 22. The numerous granitic veins so w^ell known to mii 

 ogists in the mica-schists and gneisses of New Hampshir 

 sachusetts and Connecticut, including among other i 

 localities, Grafton, Acworth, Royalston.'^Norwich, Goshen. ' 

 terfield, Middletown and JLi(M:'itii. soeiu from descriptions an ■ 

 from their mineral constiturnt.- t-. \;v '-wiWiw to those of ^h^^- 

 already mentioned. With the cxcMtioi, (,[ H ova Iston however 

 these localities are as yet onlv known tn me I'roni specimon«iiw 

 descriptions. It is notewortliy that at this last the finelv->:> 

 tallized beryls are directly imbedded in vitreous quartz. ; 

 same is the case with the blue and green tourmalines of ' 

 A remarkable example of a vein of this character O'- 

 Buckfield, Maine, described to me by Prof Brush, wlir. 

 isolated crystals of white orthoclase, nearly colorless nri- 

 and brown tourmaline occur in a vein of vitreous <in:tr" 

 Paris and at Hebron, Maine, tourmalines arc found per^ ' 

 crystals of quartz. The flattened tounnalines and ,- 

 found m muscovite at several localities in New Engbn:^ 

 well known to collectors, and a curious example of enci>- 

 has been observed by Prof. Brush at Hebron, where cry^ta-- 

 "''i'oo^l^ ^""^ encased in lepidolite. . , ,,. 



.M3. The following list Includes the principal rninera. -i 

 cies found in these oranitic veins in New England: apjt;^; 

 amblygonite, triphylline, autunite, vttroccrite, orthoclase, ulw^; 

 oligocase, spodumene, iolite, muscovite, l)iotite, \^V^^. 

 cookeite, chlorite, chlorophyliite, garnet. epid<>te, tomW ; 

 beryl, zircon, quartz chrysoberyl ■uitotnolitc cassitente. rut.' 

 brookite, uraninite columbite rivrochlorc sciieelite and bii=f!^'^' 

 tite. As I am not'aw.nr^ ti,.f' JlJo.lf. I.m^ hitl,<>rto boon me"- 



