Vol. 70.] 



OF THE COUXTBY AROU>D HU>"TLY. 



289 



Below are tabulated the analyses of a rock from each group, 

 together with a rough calculation of the mineral composition. For 

 comparison, two analyses are added, one taken from Mr. Winchell's 

 paper, the other from that of Prof. Lacroix. While the Huntly 

 rocks are more basic, the chief discrepancy lies in the amounts 

 of magnesia. Potash is also much higher in the Huntly rocks. 

 These discrepancies seem explicable, only on the assumption of 

 the existence of some power of selective absorption in the magma. 



Analyses of Cordierite-Norites. 



• 



IV. V. VI. 



VII. 



SiO , 



48-00 49-38 52'84 



0-99 1-24 — 

 24-74 22-03 23'62 



51-30 



25-20 

 2-91 



8-39 



2-50 

 4-01 

 0-79 

 3-82 



0-55 



99-47 



TiOo 



Al.,6, 



Fe.,0, 



0-18 

 0-21 



trace. 



11-03 

 0-24 



nt. fd. 

 0-06 

 0-99 

 9-94 

 1-47 

 0-84 



trace. 

 0-06 

 0-97 

 0-06 

 0-59 



3-11 0-65 



Cr"0. ? 



— 



— 



V o 0, 



FeO 



11-66 



MnO 





0-43 



(CoNi)O 



BaO 



CaO 



2-58 3-92 

 3-84 3-16 

 1-84 0-67 

 3-63 2-64 



0-09 h i. 87 

 0-34 J 187 



MgO 



K,0 



Na.,0 



Li,0 



H o Oatl05°C. ... 

 H."0 above 105° C. 

 P,0 



FeS, 



Totals 

 Specific gravities. 



99-74 

 2-94 





100-37 



99-80 

 2-81-2-85 



2-90 



2-88 



IV. Cordierite-norite, second group, Cuternach. Anal. E. G. Radley. 

 V. Do. do. first group, Ordiquhill. 



VI. Do. do. Minnesota. 



VII. Do. do. Quarry of Les Prinaux, Le Pallet. 



The mineralogical composition of the Huntly rocks is : — 



rv. v. 



Cordierite 53'34 



Hypersthene 1 7'04 



Biotite 14-43 



Albite 7-34 



Anortnite 4 - 72 



Ilmenite, etc 2*86 



Apatite "12 



Pleonaste "46 



Cordierite 14 - 40 



Hypersthene 3'02 



Biotite 13-53 



Albite 30-92 



Anorthite 12*23 



Ilmenite, etc 4 - 77 



Orthoclase 2-78 



Quartz 1'02 



Garnet 16*58 



Sillinianite "16 



Total 100-31 



Total 99-41 



