PHALENJ THE ROCKS OF NUGSUAKS PENINSULA 211 



Though the analyses show such 'discrepancies, especially so as 

 regards the content of the iron oxides and magnesia, the ratios in- 

 volved in the placing of the rock in its classificatory position are very 

 close. The auvergnose from the type series of von Lasaulx how- 

 ever, would, strictly speaking, be placed in the sodi potassic subrang 

 of the rang auvergnase, owing to a ratio value between the alkalies 

 of 0.61, this ratio, in the Greenland rock, being 0.2. 



NUGSUAKS PENINSULA 



On page 195 there is described a rock (Cat. No. 75,488), which 

 has been referred to as lying loose just back of Kaersut. Such ma- 

 terial is not regarded as having very great petrographic value. 

 Nevertheless, since the type is rather limited, so far as its exposures 

 in the earth's crust are known, it was deemed worthy a partial- 

 analysis to ascertain its classificatory position. From the results of 

 this chemical examination, which follow, it will be seen that the rock 

 is very basic, that it belongs to class iv, the dofemane class, section 

 four of the order hungarare, and to the domagnesic subrang of sec- 

 tion one in the permirlic rang of this order. ,Its name therefore is 

 custerose. 



Partial Analysis of Pe":idotite — Custerose 



(I) (2) 



SiO. 42.63 46.03 



AL.O3 6.88 9.27 



Fe^Os 3-32 2.72 



FeO 7.27 9.94 



MgO 29.36 25.04 



CaO 5.90 3.53 



NaoO 1.26 1.48 



K.0 14 .87 



MnO 36 .40 



NiO 27 — 



Cr^Os 0=; — 



H.O — ■ .64 



P2O5 — .17 



97.45 100.09 



Note. — i. Partial _ analysis of peridotite (custerose), Greenland, W. C. 

 Phalen, analyst. 2. Analysis of peridotite, near Querida, Silver Cliff, Custer 

 Co., Col., L. G. Eakins, analyst. Cross, 17th Ann. Rep. U. S. G. S., 

 pt. II, p. 284, 1896. 



There remains but one rock, quartz monzonite, whose microscopic 

 analysis is given on p. 206. This rock, whose chemical analysis is 

 given as follows, proves to be a dellenose. 



