446 Pirsson and Washington — Geology of New Hampshire. 



If we neglect the small amount of K 2 which is in the 

 micas and consider all of the lime and alkalies shown by the 

 analysis as in feldspar, the total weight of the latter thus cal- 

 culated would be 60' 15 per cent while the above by measure- 

 ment gives 61*90 per cent. The andesine was determined as 

 Ab 5 An 3 by a number of measurements. If we take the 

 amount of lime shown by the analysis and convert it into 

 Ab 5 An 3 it gives 34-30 per cent and the amount of soda-ortho- 

 clase remaining would be 25*85, which is not a bad agreement 

 with that obtained from the measured areas, especially if one 

 takes into account the fact that some of the un twinned areas 

 of andesine are liable to be measured as orthoclase. 



Chemical Composition. — This is shown in the following 

 analysis, No. 1 of the table : 



I II III IV v 



Si0 o 69-76 69-70 69-43 68*11 T163 



Al o 3 18-22 18-72 15-74 15*80 *178 



Fe" 0, 0-25 0*65 0-93 1*97 *002 



FeO^ 1-59 0*79 3*35 1*87 '022 



M^O 0-40 0*45 1-35 0*96 '010 



CaO... 2-68 2*25 2*07 2*43 '048 



Na o O._\ 4-06 5*01 4*56 4*40 , '066 



Kfi 2-06 T68 2-99 2*80 *022 



H 2 OllO°+--.- 0*50 0-71 *10 0*54 



H 2 OllO°- ... 0*15 .... -16 



C0 o none x= "75 



Ti0 2 0-36 .07 *005 



Total 100-03 99-96 100'52 99"87 



I. Biotitic grano-lassenose (granite-diorite-aplite ?). South end 

 of Piper Mt.," Belknap Mts., N. H. IT. S. Washington analyst. 



II. Lassenose (quartz porphyry) ; Kawishiwi River, Minnesota 

 (Grant, An. Rep. Geol. Nat. His. Surv. Minn., p. 43, 1893). A. D. 

 Meeds analyst. 



III. Lassenose (andengranit); Juncal Valley, Argentina (Stelz- 

 ner, Btr. Geol. Arg. Rep. I, p. 208, ]885). II. Schlapp analyst. 



IV. Lassenose (granite) ; Miihlberg, Odenwald, Hesse (Chelius, 

 N. J. 1884, II, p. 419, x = P 2 5 0-62 ; S0 3 0*13). 



Y. Molecular ratios of No. I. 



While some of the combined water shown by the analysis is 

 of course in the micas, the amount seems too large for the per- 

 centage of these minerals present. The high alumina, which 

 as seen in the calculation of the norm cannot all be referred to 

 feldspar, is also too great for them and the micas. This might 

 indicate some kaolin, but the rock appears remarkably fresh 

 under the microscope and kaolin is absent. It is difficult to 

 know to what to attribute the high alumina. Nothing seen in 



