1877.] 237 [Wadsworth. 



pronounced to be basalt, diabase, melaphyr, syenite, aphanite, diorite, 

 impure limestone, chlorite-schist, etc., etc. 



A want of time and the pressure of my other duties compels me to 

 present this paper without the further investigations that should be 

 made, especially as no two sections of the same rock will tell exactly 

 the same story ; I must therefore look to the future to substantiate or 

 overthrow my conclusions. 



Although no one but myself is responsible for the ideas put forth, 

 or the errors contained in this paper, I desire to acknowledge my 

 indebtedness to Professor Cooke, who kindly allowed me the use 

 of his magnificent microscope, polariscope, and foreign collection of 

 thin sections; to Professor Pumpelly, who, although I had not the 

 slightest claim upon him, most kindly taught me to make my own 

 thin sections, and gave me much valuable instruction; to Professors 

 Whitney, Hunt, Shaler, Huntington and others, for the privilege of 

 examining their lithological collections, and for other favors. 



On the Granite of North Jay, Maine. 

 By M. Edward Wadsworth. 



The granite quarries at this place are located upon a ridge of 

 granite that rises to the height of two to three hundred feet above 

 the M. C. R. R. station, and extends in a north and south direction 

 for about half a mile. 



The country rock is a mica schist. The granite has the usual con- 

 centric and cross jointing. In some parts it is quite gneissoid, and 

 in the southern and central parts of the hill is much intersected by 

 veins and coarse patches of granite, the best and finest rock being 

 on the northern portion. 



The granite is composed of orthoclase, clinoclase, muscovite, biotite 

 and quartz, and in the veins and coarser parts tourmaline, beryl and 

 garnet occur. 



The clinoclase, determined by the method of Des Cloizeaux 

 (Comptes Rendus, Vol. lxxxii, page 1017) is found to be oligoclase. 



The orthoclase shows well in polarized light the cross-hatching 

 described by Hull, Rutley and others. 



The quartz and feldspar show under the microscope the usual in- 

 closures, and the quartz in some places is filled with trichites, closely 

 resembling the usual " macroscopic " inclosures of rutile. 



