404 JOSEPH H. PERRY 



was three feet down ; the second, four or five feet below the first ; 

 and the third, twenty-five feet or more below the second. In 

 working the rock it is necessary to cut the rock horizontally as 

 well as vertically. The size of the blocks that may be taken 

 out is limited only by the strength of the derricks. The few 

 joints seen were parallel with the side of the mountain, indicat- 

 ing, as the mountain has been produced by erosion, that these 

 joints are due to causes acting since the formation of the moun- 

 tain. 



The orthoclase of the Conway granite is of a reddish tint, 

 and is so abundant as to give its color to the rock. This feld- 

 spar occurs in coarse particles an inch or so through, which fre- 

 quently show Carlsbad twinning. These particles do not present 

 the definite outline of crystals, and do not %\v^ a porphyritic 

 appearance. In addition, there is a white feldspar much less 

 abundant, and distributed irregularly, and also in irregularly 

 shaped cleavage particles much smaller than those of the ortho- 

 clase. This is a triclinic feldspar, and is twinned according to 

 the albite law. 



The quartz is generally distributed in irregular granular 

 masses varying in size from one-half inch to one inch through. 

 It is of a decided smoky-gray color, and, in contrast with the 

 red feldspar, gives a mottled appearance to the rock surface. 

 The quartz masses frequently inclose grains of both the red and 

 white feldspar. There is also quartz distributed in finer particles 

 inclosed in the orthoclase, and entirely separated from the 

 coarser granular masses. These second quartz particles are gen- 

 erally anhedra, but somewhat frequently show distinctly the 

 angles and faces of crystals. This clearly indicates that not all 

 of the quartz crystallized last in this granite, but that a part 

 crystallized before, or along with, the feldspar. 



The biotite of the granite is small in quantity, of full black 

 color, and occurs in small, foliated particles rarely- more than 

 one-sixteenth of an inch in length or width. It is generally dis- 

 tributed with the coarser granular quartz masses, though some 

 finer scales are inclosed in the feldspar. 



In addition the rocks contain a little magnetite. 



